Continuity mistake: When Butch finds he has a letter delivered from a Dame, his fur is coloured black. When Butch reads the letter aloud in the next shot, his fur is grey.
Continuity mistake: When Tom pushes Butch on the lounger when he is singing to Toodles, you can see that Butch is holding a guitar in his left hand when Tom stops at the diving board, but when Butch comes crashing down on the board in the next shot, the guitar is nowhere to be seen.