Here is the full list of all 12 Flashback trophies - there are 7 bronze, 4 silver and 1 gold.
Complete level 1 (Jungle)
Complete level 2 (New Washington)
Complete level 3 (Death Tower)
Complete level 4 (Earth)
Complete the game on Easy
Complete the game on Normal
Complete the game on Expert
Without using Rewind on Easy/Normal
Without using Rewind on Expert
Kill an enemy indirectly
Kill 50 enemies
Kill 200 enemies