Continuity mistake: In the scene where Marcus reads the comic showing the origins of Big Daddy and Hit Girl, we see a closeup of the last but one page, but when Marcus holds the comic book up to Damon in the next shot, the page is completely different to what it was before.
Continuity mistake: After swimming in the pool, Aron, Kristi and Megan pose for a picture. The feathers in both girls' hair are on their right. When Aron presses the shutter on the camera, the feather in Megan's hair has switched to her left.
Continuity mistake: After Teddy takes his dead daughter's shoe off, its position changes between angles.
Continuity mistake: When Hiccup tries to lure Toothless with the fish, he drops his knife on the ground. In the next shot, the knife moves closer to him. (00:28:45)
Character mistake: In the scene where Carrie is printing an article she has written, the title reads: The Terrible Two's. A successful, educated writer would never have used an apostrophe to pluralize a word. Ever.
Continuity mistake: When Eduardo finds the letter on the mantlepiece about them apparently stealing the idea for Facebook and asks Mark if they did or not, he places a bottle on the mantlepiece just before he finds the letter. This bottle rotates slightly between shots without him touching it after placing it down. (00:49:15)
Continuity mistake: Marion is guiding a plow horse when a man comes to collect more tax. As she turns to tell him that her father-in-law is too poor to pay him, her long braid, which has been in front of her right shoulder, is now hanging behind her.
Continuity mistake: Near the end of the movie, Ethan tells Peter that he had his wallet all along. Peter steps forward from the car wearing his glasses. In the very next shot, they are gone and nowhere to be seen. (01:16:30)
Continuity mistake: When Dewey and Gilleece are in the rail roller truck, the tailgate of the truck is clean with nothing on it. After the attempt to climb on 777 fails and the door gets smashed off, the tailgate suddenly has some kind of equipment either attached to or exposed off the tailgate in the middle.
Visible crew/equipment: Near the end of the movie while Will Ferrel is going to the bathroom in his house, the camera person is visible in the mirror off to the right of the screen.