Continuity mistake: When Sylvester attempts to run into the house, Bugs Bunny closes the bottom half of the door and Sylvester crashes right into it. But when we see Sylvester dazed in the next shot, the top half of the door is nowhere to be seen.
Continuity mistake: When Granny wonders where Sylvester is, Bugs Bunny drops his carrot on a skewer on the fireplace to bring Sylvester in, but when he is drawing a picture of Sylvester, the carrot is nowhere to be seen.
Continuity mistake: When Bugs Bunny is drawing a picture of Sylvester, you can see that the drawing board is on Bugs' knees, but when we see him drawing a picture of his hand in the next shot, the board is now between his legs.
Continuity mistake: When Sylvester thinks he's killed Bugs Bunny, the snowman melts on the pillow and leaves a huge puddle of water, but when Granny asks "What's going on down there?", we return to Sylvester and Bugs and the puddle has disappeared.
Continuity mistake: When Granny is speaking to Sylvester at the start of the cartoon, you can see there is nothing is under Sylvester. In the next shot, a green pillow appears, and in the shot after that, it has disappeared.