Revealing mistake: When Will flies back in through the window and picks up Royal Pain, you can see that the back of Will's jacket is sticking up, which was where the harness was lifting him up. (01:24:05)
Revealing mistake: There are multiple times throughout the movie when the "wind effect", the hair of the characters being blown up by wind off of Speed's super speed, is not in sync and occurs prior to Speed actually zooming past. The 2 most notable occurrences of this are when Speed steals the pudding from Ethan and moves next to Lash and when Speed steals the Pacifier from the secret sanctum.
Revealing mistake: When Layla and Will are sitting on Will's roof, after she grows an apple for him, in one of the following shots when she's turning it around in her hands the apple has a visible plastic seam. (00:26:20)
Revealing mistake: The commander raises his arms,clenches his fists and grimaces in pain before the beam from The Pacifier hits him.
Answer: Voices carry.