Here is the full list of all 12 Flashback trophies - there are 7 bronze, 4 silver and 1 gold.
Obtain 100% in World Exploration
Obtain the maximum level for every upgrade
Conrad has to reach level 30
Kill 200 enemies with explosives
Kill 500 enemies with the Heavy Shot
Complete the game in Hard Mode
Complete the game in Normal Mode
Complete the game in Easy Mode
Complete all VR challenges
Kill 50 enemies with a melee attack
Kill 50 enemies by finishing them
Kill an enemy by finishing him