Continuity mistake: In the scene showing Groucho being chased across the cars as they enter the race course, in the shot from behind you see him running along the rail only to slip, the following shot is from the front and shows the same slip he's already made.
Continuity mistake: The lion on stage has a spotlight shining down on him from the top left at him in center stage. But about a minute into the song, suddenly the spotlight is now shining from his immediate right and perpendicular to the stage. Moments later, it is back from above to the left. (00:03:10)
Continuity mistake: In a saloon, Moe and Curly are playing poker with Longhorn Pete, the proprietor. Among Curly's five cards are an ace of hearts and an ace of diamonds. Moe's cards include an ace of spades and an ace of clubs. They pass some of the cards to each other under the table in the hope that one of them will wind up with all four aces. When their cards are shown again, Curly and Moe each have an ace of spades and ace of clubs. The ace of hearts and ace of diamonds have disappeared.
Continuity mistake: When Porky arrives home, you can see a window looking outside to the right of the front door, but when Porky shoots the man upstairs a second time, the front door now leads to a hallway with a staircase.
Continuity mistake: When Stan and Ollie arrive at Brushwood Gulch, they show Mickey Finn the deed they've got for Mary Roberts, and it has a couple of holes in it from where Stan has been keeping it in his shoe; Ollie even unfurls it to show the camera it's got holes. But in every other shot after that, whenever the deed is shown, it's got no holes in it whatsoever and is perfectly clean.
Continuity mistake: When Goofy searches through the dresser drawers one of the ghosts causes trouble, then Goofy breaks through the top of the dresser and winds up trapped inside, but when all four ghosts appear the dresser top is perfectly fine and that damage has vanished. Also, two of the drawers (one large and one small) fall out of the dresser, but as the four ghosts are pushing the dresser those two drawers have reappeared in their proper places.
Continuity mistake: When lawyer Goodwill is in the secret laboratory, he picks up a bottle that has "Jekyll and Hyde Juice" written on the label, but when we see him with the bottle in the next shot, the words have disappeared.
Continuity mistake: When we see the animals change seats at the start of the cartoon, you can see there is an aisle in the middle of the theatre, but when the show begins in the next shot, the aisle has disappeared.
Continuity mistake: The entries into Quartermain's journal are supposedly covering events during 1881 and 1882. The entries consist of a day and a date, but no month. Taken in order, they cannot fit into the 1881-1882 calendar. For example, the two entries immediately before the June eclipse can only be in August 1882.