When Mary is filming her first bit part she drops her script on the stairs, which then disappears between shots.
As Lowell Sherman, playing Max Carey, enters the Brown Derby, the entry door at the actual exterior location changes from multi-paned to single-paned at the interior, soundstage set.
When the screen shows a newspaper gossip column, we can see part of an item relating a joke about a Jewish boy and a bird. Several months later, another gossip column shows the identical item.
Near the beginning of the film, when Mary is posing with the magazine photo of Clark Gable, this scene is visually flipped horizontally. The magazine print is reversed, as well as the part in Mary's hair, which instantly moves from the right side of her head to her left.