Deliberate mistake: At the beginning of the movie Mr. Coates tells his wife that he will be gone "all of three months, maybe four." The first time we see Bud and Elizabeth Searcy she tells Travis that her dog is pregnant and that Old Yeller is the father. We then see her dog that does not look very pregnant. The next time we see Elizabeth she presents Travis with one of the pups. The problem is that the pup that was supposedly just born is about 4 months old.
Continuity mistake: When Tom is placing a chicken under Spike's arm, Jerry takes a photo and you can see a trail of fake paw marks. When Jerry emerges from the dark room with copies of the photo, he takes one copy from the pile and has a look at it, but the picture shows no paw marks at all.
Continuity mistake: When Ralph is walking up the steps to his apartment, he has a present in his right hand. The present disappears when he goes through the doors, but re-appears when he enters the kitchen.
Continuity mistake: When Quackie catches up with the mysterious man in his carriage, he is initially sitting by the window, but when he is speaking to Quackie, he is now sitting by the door.
Continuity mistake: When the St Bernard dog comes to the rescue, he pulls a frozen Sam out of the snow that had fallen on him. But when the dog leaves after drinking the martini, there is no sign of Sam.
Continuity mistake: When the three pigs are listening to the wolf playing his trumpet in Hell, the position of the double bass behind the pig who is playing the piano changes between shots.
Continuity mistake: When Daffy arrives at the theatre, there is a billboard behind him saying "Bijou Presents on Stage Tonight." But he points to the marquee in the next shot, the words have disappeared.