其實這不是我寫的，是一些老外整理的，我只是把連結給大家看看而已（汗）。
因為老外使用的是美版，所以下面的影片內容跟文字版內容都是英文，
使用日文版的玩家請自行看影片的時間點斟酌一下日文版的flashback出現位置。
順帶一提，下方文字版內容還包括各幻聽（不中斷聽完可以獲得1000DP）的出現地點，
這些項目前面註明了「AUDIO」或「GAMEPLAY」，
有些地方還提到自動的flashback（例如跟liquid CQC肉搏戰的期間），
不過遊戲中並未把這些部分計算在flashback的數量之中，
所以我想這兩個部分應該跟「看完所有flashback」獲得的獎盃無關。
==============================================================
※資料來源：http://ppt.cc/-4XN
（這裡還有所有獎盃的攻略方法，有興趣的玩家可以參考參考）
※Youtube影片版：http://ppt.cc/yjvn
※文字版：
ACT 0
‧At the end of Act 0, when Snake is saluting at the graveyard.
‧At the same cutscene as above, when Snake mentions FOXDIE.
‧The third flashback of this cutscene is when Otacon mentions Naomi.
‧The final flashback of this cutscene is after the helicopter took off and
Otacon says “We have found him”, referring to Ocelot.
ACT 1
‧When you meet with the Mk. II Otacon delivers to you, when Otacon says
that the Mk. II resembles to Metal Gear REX.
‧When you meet with the Rat Patrol Team, Akiba is threatening you with a
gun. The flashback is available when Snake calls him "Rookie".
‧At the same cutscene as above, when Meryl puts off her mask and reveals
herself.
‧The final flashback for this cutscene is when Akiba gets on his knees
because of his stomach problems. Snake asks him if he is ok.
‧At the cutscene where we first meet Liquid, at the point where his name
appears and he is introduced.
‧Later at the same cutscene, where you are almost unconscious, Naomi will
appear with a syringe and inject herself. That's your chance for the
flashback.
ACT 2
‧During Mission Briefing, when Otacon mentions Meryl and her boys that they
are fine.
‧During Mission Briefing, during a pause before Snake mentions Naomi.
‧During Mission Briefing, when you see the video with Naomi and she mentions
the FOXDIE.
‧During Mission Briefing, when Snake and Otacon are viewing the Soliton
Radar data from Shadow Moses.
‧During Mission Briefing, this is the last flashback in the briefing
immediately after the last one, when Otacon mentions Mei Ling.
‧At the first cutscene of the act, while Snake is crawling and mentions
Solidus.
‧Later in the same cutscene, when Vamp is introduced.
‧When you meet with Drebin, you will have multiple flashbacks when seeing
the pictures of the B&Bs while he's telling you their names.
‧Shortly after, when Snake mentions all these bad guys from the first Metal
Gear Solid game.
‧Next in the same cutscene, Drebin will say "Keeps this whole mess in check".
This is where the flashback will appear about the Patriots.
‧When you meet Naomi and she is introduced, she will immediately mention
Shadow Moses and the flashback will appear.
‧After you save the game, when Snake mentions about FOXDIE having killed
the AT President and Liquid.
‧Later in the same cutscene, when Naomi tells you about a new strain of
FOXDIE and Snake says "Him!" referring to Drebin.
‧After you get out of the laboratory, at the cutscene where Snake is
looking on the ground to track down Naomi. The flashback appears when he
pulls out his knife and try to figure the footprints.
‧（AUDIO） While searching for Naomi, you will come across a river. Take
the left path and you will soon find yourself in a strange area with
circles in the grass.
‧At the cutscene where you enter the city with the van Drebin is driving and
get ambushed by Gekkos, when Naomi and Snake hold the monkey hand by hand.
‧At the same cutscene when Raiden is introduced, takes down the Geckos and
sheathes his katana.
ACT 3
‧During Mission Briefing, when Naomi is with Sunny, you will see after a
while a picture in the wall. Sunny will tell "Her name was Olga" and you
can get the flashback of Olga from Metal Gear Solid 2 at that time.
‧During Mission Briefing, when Snake comments “So that’s what Liquid was
talking about”.
‧During Mission Briefing, when Naomi is looking at a blue screen. It's near
when Naomi says "Liquid has already left for Europe in search of Big Boss'
body".
‧During Mission Briefing, when Naomi kneels in front of the lying Raiden
shortly after the previous one. You get the flashback of Grey Fox from
Metal Gear Solid 1.
‧During Mission Briefing, much later, when Naomi and Otacon look at the
computer at the picture of Otacon's sister Emma.
‧When you meet with Big Mama, after a series of cutscenes, she will shoot
and destroy a dwarf Gekko. When she shoots at it, her flashback will appear.
‧In the same cutscene, when you start to prepare for departure, Big Mama
will comment "Nowadays, anyone with a computer can get a combat training".
This is when the flashback appears. This is a pretty funny one as it
actually shows you footage from the game.
‧After the bike sequence, when Big Mama is injured. She will pull herself
out of the piercing junk and the flashback will appear.
‧Near the end of the same cutscene, when Snake gives Big Mama a weapon to
protect herself, the flashback will appear when she says to him "Promise me".
‧After defeating Raven and meeting with Big Mama again, when you are about
to head off in the sewers, she will have a look at her destroyed bike and
that's when the flashback appears.
ACT 4
‧During Mission Briefing. This is a little hard to point out. It is when
Sunny is starting getting down the stairs and Snake and Otacon talks about
the Patriots' AIs.
‧During Mission Briefing, when Snake is wondering about Liquid's plans.
It's near the middle of the cutscene.
‧（AUDIO） In the middle of the Helipad in the Heliport Area.
‧（GAMEPLAY） When you reach the base at the Heliport, approach the
security camera guarding the stairs and tap to get a flashback. Note that
the song must be still playing in order to get this flashback.
‧（GAMEPLAY） Aim the Mk.23 after acquiring it.
‧（AUDIO） Near the elevator south of the Helipad.
‧（GAMEPLAY） Move the camera directly overhead and move around.
‧（AUDIO） Go and enter the Tank Hanger via the vent near the main door or
in the balcony instead of the main door.
‧（AUDIO） Ground Floor of the Tank Hanger.
‧（AUDIO） Starting point of the Canyon Area.
‧（AUDIO） Electric High Voltage room in the Nuclear Warhead Storage Bldg B2.
‧When you get to Otacon's old office, after you put the password, Snake will
look at the office for a bit and look at a closet.
‧At the same cutscene, when Otacon tells Snake about Naomi having stolen his
blood.
‧A bit later, when Otacon mentions REX's old underground hangar.
‧A few seconds after the last flashback, a new one will appear when Snake
mentions the old days about the doors requiring keycards.
‧（AUDIO） Otacon's Office near the locker.
‧At the cutscene after you defeat the Crying Beauty and talking to Drebin
about her past, when a wolf comes to mourn about the Beauty.
‧（AUDIO） At the crashed Hind D in the Snowfield.
‧（AUDIO） In the middle of the path leading to the towers.
‧（AUDIO） On the second floor of the south tower.
‧（AUDIO） Near where you beat the Crying Beauty.
‧（AUDIO） During the elevator ride after the Dwarf Gekkos.
‧（AUDIO） Enter the Underground Base area. Once there, crawl through the
small vent space and to your right is a closed door to the freezer
warehouse where you fight Vulcan Raven in Metal Gear Solid. Approach the
door and an audio flashback should trigger.
‧When you enter REX's old hanger, Snake and Mk. II will look at the whole
place making the flashback appear.
‧After beating Vamp, and when Naomi is staying behind and Otacon says "Why
does it always end this way?". Truly a magnificent Metal Gear Solid moment.
‧At the very end of the Act, after you defeat Ray, at the part where Raiden
comes to save Snake. From the moment Raiden mentions Rose, start tapping
and do not stop until the cutscene ends. There are many hidden flashbacks
here, meaning the will not appear in the screen. Credis to Zyrodra.
ACT 5
‧During Mission Briefing, when Otacon is speaking about Naomi near the
middle of the cutscene.
‧During Mission Briefing, when Otacon is telling to Snake that Naomi was
making a program and she handed it to Sunny.
‧During Mission Briefing, near a minute after the last flashback, when
Otacon mentions Emma.
‧When Screaming and Psycho Mantis are introduced, you will get the next
flashback.
‧During the encounter with Psycho Mantis, there will be a flashback about
the Memory Card AND another one for the Vibration. These are the two
funniest flashbacks in the game.
‧As soon as Psycho Mantis is exploding start tapping You will see a hidden
flashback of Hideo Kojima.
‧After Psycho Mantis is gone, you will hear a voice saying "The spirit of
the warrior will always be with you." That's when the flashback of The
Spirit from Metal Gear Solid 3 appears.
‧When Meryl and Akiba do their last stand, when Akiba mentions that he has
no nanomachines in his body.
‧Later in the same cutscenes, when Meryl finds out why Johny had
stomachaches back in Act 1.
‧A few seconds after the last one, when Johny says about first meeting
Meryl in Shadow Moses.
‧There is a series of flashbacks during the final fight, but all these are
automatically given to you. No need to tap here.
‧In the final final cutscene before the Debriefing where Drebin and Otacon
are talking together, the flashback appears when Drebin is talking about
his family.
DEBRIEFING
‧After the cutscene about Solidus, another cutscene with Big Boss speaking
will start. Immediately at the beginning when Big Boss says "someone can be
made to play a specific role".
‧When Big Boss saying that all the original members have passed on and only
Zero is left.
‧When Big Boss is killing Zero.
‧When Big Boss is saying the virus Zero planted in Snake, is killing him.
‧A few seconds later, when Big Boss said that the virus inside Snake killed
EVA and Ocelot.
‧When Snake carried Big Boss and the last one looks at his patriot.
‧When Big Boss salutes at the graveyard. Another superb Metal Gear Solid
moment as well as the final flashback in the game.