When Abbott unfurls the newspaper to look for the pictures of the dead Dr. Zoomer, it is apparent that there is no printing on any of the interior pages; all the sheets are blank white.
After Bud and Lou switch burgers in the cafe, Lou eats the medallion in pieces yet, when he's X-rayed later, the medallion is intact.
About 20 minutes into the movie, Bud and Lou are sitting at a cafe and Bud buys a newspaper. In a two-shot, Bud starts reading the main story which he says has a picture blaming him for the murder of Dr. Zuma. But the newspaper he holds is a blank white piece of paper. When the camera cuts to a close up of the paper, there is a photo of Bud. Then it cuts back to a two-shot of the boys and the newspaper is completely blank again.
While the boys are digging the hole, and after Lou has disappeared; Abbott sits down in the same place. Abbott is tipped backward, head first through the wall; but when he falls into the room below though a small hole in the ceiling; he comes through feet first.
Upon returning to Dr. Zoomer's home, Bud and Lou are wearing Egyptian robes. But after encountering Madame Rontru's henchmen, the boys go back to sporting the pith helmet costumes they wore during their first visit.
Bud and Lou play back recordings on Dr. Zoomer's reel to reel tape recorder multiple times, but they never once rewind it.
Roughly 10 minutes into the movie, Lou opens a closet and sees Dr. Zuma sitting there with his eyes open. Lou doesn't know Dr. Zuma is dead and tries to take a picture but a coat is in the way. When Lou moves the coat Dr. Zuma's eyes close as he falls.
There are no appaloosa horses in Egypt.
When Dr. Zoomer is recording his entry at the point he says 'look there' and is killed he gasps quietly. Yet later when Costello plays back the recording at the point where Dr. Zoomer says 'look there' and is killed there's a loud scream on the recording instead.
Though Bud Abbott's character in this film was named Peter Patterson and Lou Costello's character's name was Freddie Franklin, they addressed each other by their own, real names ("Heeeeey Abbott!") throughout the picture. The credits are the only place where their characters' names are used.
Towards the end when all three mummy are running around, Abbott reaches back and says, "Come on, Costello" instead of using his character name of Freddie.