Continuity mistake: After Tom says goodbye to his friends, he goes to sleep on the window ledge. At this point, you can see it's night time, but when we see him sleeping from inside the house in the next shot, it is daylight outside.
Continuity mistake: When Bugs (dressed as a female hunter) walks up to Elmer after nearly hurting him with her gun, Elmer hides his rifle behind his back, which subsequently disappears.
Continuity mistake: When Tom is throwing dynamite into Jerry's mouse-hole, you can see he is surrounded by sticks of dynamite, but when Muscles marches out of the hole with the dynamite, the sticks have disappeared.