Other mistake: Whenever Leon reloads his Shotgun, Riot Gun or Striker, he always puts in two shells, regardless of how many are actually reloaded.
Other mistake: After fighting the lake monster, if Leon is wearing his police uniform (unlocked after beating the game), in the next cutscene he has a nightmare about the Las Plagas in his body. He looks down at his arm (which is now infected with the Las Plagas) and screams, but since the jacket is covering his arm, he would not have been able to see it.
