Continuity mistake: When Sam (dressed in a suit of armour) tries to cut off Bugs' head with an axe when Bugs reaches the top of the stairs, he falls off the stand with the axe, but when he falls down the stairs, the axe is nowhere to be seen.
Continuity mistake: When Sam knocks on the bathroom door, he says "Get outta there!" and Bugs opens the door on him. You can see that Bugs opens the door outwards when this happens, but when Sam barges in on Bugs later on, the door opens inwards.
Continuity mistake: When Sam runs into the closet after Bugs asks him for some olives, he opens the door and you can see the back of the door is completely clear, but when we see Sam ranting and raving, panels have appeared.
Continuity mistake: When Sam says "Salt? Why didn't you say so?" at the dinner table, you can see there is a knife next to his plate, but when he leaves his chair to take the salt shaker to Bugs, the knife has disappeared.
Continuity mistake: When Bugs reaches the top of the stairs in Bedlam Manor, Yosemite Sam (dressed in a suit of armour) tries to chop off Bugs' head with an axe, but Bugs ducks and Sam falls down the stairs. When we see Sam falling down the stairs in the next shot, Bugs has disappeared.