When the patrol planes are shown in the wide shot, they are seen as pre-WWII biplanes, but when they switch to a close-up of a pilot's double-take, the plane has the correct WWII cockpit.
When the Stooges enter the house, a pipe threader magically appears in his left hand with the tool belt.
When Curly is trying to get boosted up to the telephone pole, Moe's hair changes from combed forward to parted.
When Curly mistakenly knocks out Moe and Larry, who are disguised as Hitler and his Japanese assistant (Hirohito?), a lamp behind him accidentally falls down. Then, in the next scene, the lamp is back up on the table.
When Curly disconnects his telephone pole seat, you can hear the wire actually hitting the studio floor, even though Curly is supposed to be 30 feet in the air.
When Curly calls Larry over to help him with the wiring trouble, he says "Gimme a help!" instead of 'Gimme a hand."
A crew member's hand is seen on the right side of the screen tossing the bowl of cake batter on the cook's head.
The wire holding the submarine can be seen, as well as vertical splash marks from the wire in front of the sub.