I don't really bealeave all of these are mistakes.. I am sure some are some just to add some extra interest?
Mistake: During the shoot out with the pirates on their secret island, Team Zissous' firearms change from Glocks 21's to Beretta 92FSs'. When the members are holding the guns without firing, they are in fact Glocks. Any scene where they are actually shooting, they are holding Berettas.