During the scene when Wally gets hit by the soldier in the cafe, and Wally bumps into another soldier, causing him to go into a cake, take notice of how much cake is on him throughout the different camera shots. Also Pops (the owner) starts to wipe the cake off of the soldier's face. The amount of cake changes between shots.
1941 was directed by Steven Spielberg. The movie opens with a spoof of "Jaws", which Spielberg also directed. The woman who swims out and winds up on the submarine is the same actress who was eaten at the beginning of Jaws.