Other mistake: Mace's reflection can still be seen on the pond after he disappears. (00:53:30)
Continuity mistake: At the start of the film, Hanjuro intimidates a bodyguard by crushing a golf ball with his hand. In the initial shot, his palm faces outward. In the next shot, his palm faces inward. (00:03:55)
Continuity mistake: At the beginning of the film, the young Roy breaks a board of the hen-house wall with a pitch. When the shot cuts back to the hen-house wall a moment later, the hole is a different shape and in a different place.
Revealing mistake: When Hanks drives through the city escaping form the MPs, the guy driving is a very obvious stuntman.
Continuity mistake: The note Jenny puts up in the restroom changes; when Starman goes into the bathroom while Jenny is signing the receipt, notice that the postage stamps holding the note to the mirror are now in different positions and the word "help" is smaller. (00:35:55 - 00:36:45)
Continuity mistake: When Jackie jumps off his balcony the first morning, the Spanish grocer is ducking with his hands above his head, while in the close-up of Jackie landing he's using his hands to shield his veggies. (00:04:00)
Suggested correction: This isn't a mistake. That's him, under the water in the same pose he was in before he touched the water.
After watching the scene, the mistake is valid. When he's underwater, he's not in the same "pose." That would require him to be upside down and squatting. But that's not the pose we see him in.
Bishop73
We see Mace semi-kneeling and reaching out to touch the water when he vanishes, but his upside-down reflection is still in the exact same calm position even when he's gone, and in the next shot we see Mace under the water right-side up, with his arms reaching up to the surface. This is a valid mistake, the suggested correction is not right.
Super Grover