Continuity mistake: In the scene towards the end of the film where we see Slade's body fall, it falls onto a submerged rock just below the surface of the water and there is a splash of water. In the next shot Tarzan looks down from the cliff above and Slade's body is on a large dry rock, a little distant from where the body originally fell.
Continuity mistake: Judah Ben-Hur removes the large ring he had received from Arrius and gives it to Pontius Pilate to return to Arrius. Following this, he returns to the leper colony with Esther, and he reunites with Miriam. When Judah is told Tirzah is dying, as Judah searches the cave for Tirzah, he is once again wearing the large ring he had received from Arrius, on his right index finger. Then, that ring vanishes when he finds Tirzah.
Continuity mistake: When the men first enter the spaceship, one of the windows shows an afternoon sky and the one next to it shows a nighttime sky. (01:11:20)
Continuity mistake: When in James Mason's house in South Dakota, Cary Grant writes a message to Eva Marie Saint on a matchbook from which several matches are missing. When Ms. Saint subsequently reads the message the matchbook is full.