Other mistake: Holmes appears disguised as a Sikh, complete with turban and beard. Although his face is black, his hands are without any make up and are white as snow.
Plot hole: When Holmes starts the human chess game, he says, 'Who had entered the lists, the king's pale knight.' This refers to moving the white knight of the king's side. However, the ritual does not mention to which square it should move. Still having three possible squares to move to (since the knight is on its initial square and the game has already started), Holmes knows and indicates that the knight (Dr. Sexton) must move to square F3.
Continuity mistake: When Bugs is viewing footage of the previous encounter between Cecil Turtle and himself at the start of the cartoon, you can see that viewed from behind, the projector only has one reel. When we see Bugs eating his carrot in the next shot, there are now two reels.
Revealing mistake: When the mice are feeding the cat, the cat sits up and a mouse passes through his head.
Continuity mistake: When Porky opens the door and finds Daffy dressed as a clown, the front of the door is blue but in the next shot changes to green.