Continuity mistake: If you look carefully at the monster (Frankenstein) you will see that his face is different in the ending scenes. The reason is, during the movie you see the monster take the woman doctor and throw her out the laboratory window. You then see the monster kind of stumble, which he really did and broke his ankle. So in the final scenes they replaced Lon Chaney Jr. as wolfman with a stuntman, and Lon Chaney Jr. finished the movie as the monster.
Factual error: After the first encounter with the Apaches, the covered wagon is headed to the Fort at full speed. The camera pans to the Apaches on the ridge and you can see a truck driving at the bottom right corner. (00:32:00)
Continuity mistake: The length of Edward G. Robinson's necktie rises and falls, often within the same scene.
Factual error: When the riders are watching the wagon train, in the background you can see a communication tower with conical speakers.
Deliberate mistake: The same scene of William Bendix at bat swinging and missing is used repeatedly in the film.
Revealing mistake: When the American pilots flying P-47 Thunderbolts are attacked by German fighters, the German planes are really American P-51 Mustangs painted with German markings.
Continuity mistake: In the scene where Judy Garland and Fred Astaire go to the nightclub to see Ann Miller, Ann invites Fred to come up and dance with her. When she is dancing by herself, she is wearing red high heels. When Fred comes up, she is wearing red flats.
Revealing mistake: When Howard and Curtin chase Dobbs, they pass a dead donkey which is obviously breathing, and the rope used to tie its legs together is visible too.
Visible crew/equipment: During the movie whenever Bob Hope is pulled off the wagon by his team of horses you can see a board leaning against the wagon that was used to help the stunt man when he was pulled off the wagon.
Continuity mistake: Near the end of the movie, Lucinda is severely injured in her leg, and has to hobble to walk. In the last scene (a short time later) as she approaches her home, she is walking with no problem, and has her arm in a sling.
Audio problem: When Phillip plays on the piano, the music doesn't match his finger movements.
Plot hole: When Ralls runs the Witch onto the reef, he is at the helm. As she strikes bow on, the wheel spins madly for no reason, as the tiller ropes would not have been affected by the collision.
Audio problem: In a scene when the Blandings first move into their dream house, Cary Grant (Jim Blandings) says something to a workman and his lips clearly don't match what is heard.
Continuity mistake: When Leona picks up her hand mirror, her medicine tray is positioned directly in front of her on her bed. When she puts the hand mirror down in the next shot, the medicine tray is pushed about a foot away from her bed.
Continuity mistake: When Montgomery Clift puts the boy into his jeep, the jeep has the standard seats. When he arrives at his house with the boy, the jeep has custom seats. The seats change again later in the movie also.
Revealing mistake: When Tom is punctured in the rear by the fork that Nibbles is holding, his tail is missing.
Continuity mistake: When Elmer catches Sylvester breaking his dishes, Elmer's position changes between shots.
Continuity mistake: When Chip slides down the drainpipe and holds on the frame to get to the window of Donald's house, you can see that there is nothing in front of the window, but when Chip is looking into the kitchen in the next shot, a cord has suddenly appeared.
Continuity mistake: When Yosemite Sam enters the saloon, there are swinging doors behind him. When he orders "all of you skunks" to "clear outta here", the other cowboys leave but the doors to the saloon have disappeared.
Continuity mistake: When Sylvester's conscience appears by the tree stump, the position of Sylvester's left leg on the stump changes between shots.