When Evie is on the ladder, she's holding a book that she tries to put on the adjacent bookcase. When she drops the book, there is no sound of the book landing and, when she leans over and the ladder is supporting itself, the book is nowhere to be seen.
Just before the warden is killed, you can see Rick's right wrist without his leather band and his band-less wrist has no tattoo.
When Rick and Jonathan are trying to recover the Book of Amun-Ra from the statue of Horus, holes suddenly appear in the floor of the chamber without explanation. Originally, a deleted scene had several more mummies bursting through the ground and attacking them, before being killed by the salt acid booby-trap in the statue; the sequence was cut but the holes they emerged from can still be seen in some shots.
After O'Connell, Evy, Jonathan and the Warden get out of the water, all of them have wet clothes. But, after the scene where Benny screams, they appear to have dry clothes.
When they all return to Hamunaptra for the final scene, they arrive via airplane and Imhotep's cyclone. Yet, when Bennie takes the gold and the four heroes escape, there is a herd of saddled camels just outside, Where did they come from? How did they get there?
Both times, when the Arab horsemen are attacking Hamunaptra, the sound of ululation is heard. In the Middle East, this sound is traditionally made by women, and during times of celebration or grieving. It wouldn't be made by attacking men on horseback.
The hieroglyphs on Ardeth Bay's forehead are supposed to spell Imhotep. They are, however, incorrect, and are translated as Imhotper, rather than Imhotep.
In the battle with the guards, Rick picks up a bronze sword and, in combat, sparks literally fly. Bronze weapons cannot produce sparks. Rick also uses the sword to cut the iron chain holding Evelyn. Bronze cannot cut iron and iron would not be available to Imhotep as ancient Egypt had only copper or bronze.
The "Royal Air Corps" has never existed. It was the Royal Flying Corps until 1918 and has been the Royal Air Force ever since.
When O'Connell jumps overboard from the blazing boat he throws in front of him a bag containing various weapons and ammunition but despite the weight the bag floats instead of sinking.
The term "salt acid" is used; while no longer in use, this is an old name for hydrochloric acid.
Seti I, Imhotep, and Anck Su Namun were real people, but the three of them lived centuries apart from each other. The fictitious characters in this movie named after the historic characters share no traits with their real-life counterparts.
When the lid is taken off Imhotep's coffin, Evie looks at the carving: "Death is only the Beginning." The scarabs presumably ate away his bandages, freeing his hands.
Beni jumps out of the window and breaks it. When Imhotep breathes out the flies, Rick and Jonathan close the unbroken shutters, not the broken window.
When Imhotep realizes Beni is speaking "the language of the slaves", he speaks one or two sentences in Hebrew, then switches back to ancient Egyptian, but Beni still understands him. Apparently, Beni does know ancient Egyptian (given his occupation it shouldn't come as a surprise), even though not so well, which becomes apparent when Evelyn starts correcting him. So, there is no reason for Imhotep to continue to speak Hebrew.
When O'Connell jumps off the ship into the Nile, his bag full of weapons floats when it hits the water.
When the Americans are shooting at the Medji on the boat, they are all wearing earplugs.
When the yellow car pulls up to the hotel, the wheels on the car are not turning.
Soon after the main characters pick up their camels, there is a left to right panning shot of them riding in the desert. At least five dust marks on the camera lens are revealed as pale shadows against the sand.
When Evelyn is on the ladder unsupported by a bookcase, the stunt double is obvious, especially by his shoes.
Codex-style books (pages, covers, and binding) were not invented until the Roman Empire. Ancient Egyptians used scrolls. Therefore, the Book of the Dead and the Book of Amun-Ra should not look like modern books at all.
After being hanged and prior to boarding the boat, Rick is explaining to Evelyn about his troop believing in the city so much they marched across Libya. The movie is based in 1923 and the country was not referred to as Libya until 1934.
When they seek Winston's help, the Victrola is playing at 33 rpm. Victrolas only play at 78 rpm; long-playing (33 rpm) records did not appear until the 1950s.
The plane Winston is flying is a Stampe et Vertongen SV-4B. These planes went into production in 1930, five years after the film is set.
The knife that Rick uses to cut out the scarab from Jonathan's arm is a Benchmade model 42 butterfly knife which would not have been available in 1923.
Every time we see Ardeth Bay at the beginning of the movie, he says the same phrase every time he talks, even though the translation is always different.
After Rick is thrown by Imhotep, he says "no problem" even though his lips are not moving.
When Imohtep is scared by the cat on the piano, you see the cat's paws hit the piano keys. The last pitch played does not match the corresponding key that the cat stepped on.
While on the boat, O'Connell confronts Beni. You hear the sound of a handgun being cocked. Yet, when the .45 is shown, the hammer is still down.
When Rick, Jonathan, Winston and the Americans are sitting at the bar in Fort Brydon (after the introduction of Winston), you can see 1st Assistant Director Cliff Lanning with his script in hand on the very left side of the screen.
In the opening scene where Rick and Beni are crouching behind the wall, and the camera is panning along the side of the galloping horsemen. In the background is a quite visible camera stand and two camera operators shooting the scene from another angle.
After she finishes rearranging the bookshelves, Evelyn enters a dark chamber of the museum alone. As she turns to grab a torch, a red flash of light is seen on a door to her left. Possibly a laser (such as a cinematic tape measure) or simply a reflected light by the crew. The light flash does not appear to be related to her movement.
During the car chase through Cairo, film lights can be seen.
When Rick and Evie are up on deck on the ship, and the deck is empty except for them, and Rick begins checking his guns, a crew member's shadow is visible behind Evie. It appears twice.
In the opening shot of Thebes, pyramids are visible, but there were no pyramids built around Thebes. You can also see a small version of a Sphinx in front of the pyramids, making the whole set look like Giza, in Cairo.
Rick refers to the Tuareg's beliefs about Hamunaptra, but the Tuareg do not live in Egypt.
At the beginning of the film, when Imhotep is stopped from completing the ritual to revive Anck-su-namun, her soul goes back to the Underworld. Yet later, when he's stopped from sacrificing Evelyn, it doesn't happen.
Early in the film, it is established that Evelyn needs to wear reading glasses. Later, she can be seen walking around reading a book without glasses. *People who use reading glasses can usually still read somewhat without them, if they hold the book closer or far enough away, depending on what their vision issue requires.*
After Jonathan was able to steal the key of the Book of Amun-Ra with Evelyn, he opens the book and reads the hieroglyphics upside down.
Imhotep speaks Hebrew very poorly: first, he mispronounces the words (using the consonant "w" instead of "v"); second, he makes severe grammar errors: he tells Beni "ulai uchal lehishtamesh bach" (= I may have use for you), but the word "bach" is used for female; he should have said "becha". However, he refers to Hebrew as "the language of the slaves," which makes it clear it is not his first language and he might not be completely fluent.