Continuity mistake: When Bullock is warning Reeves of the coming winter blizzard, she is looking through pictures that depicted her and her friends enjoying the snow. She then turns to the dog and asks "Remember that day? You were not happy". However it's revealed that both characters have the same dog, given to Bullock's boyfriend by Reeves, so when the snow happened in Reeves' time - 2004 - the dog was with him.
Continuity mistake: When Troy is in the locker room with his teammates, Chad is handed the framed photo of Troy's father and there's a white sticker on the back of the frame. In the next shot, when Chad gives the frame to Troy, the sticker is gone. (00:58:50)
Continuity mistake: When everybody is at the rehearsal for Grant and Julia's wedding, when Bernie does a toast to Julia and Grant, watch the level of water in Roz's glass, it changes without her even touching it.
Continuity mistake: When Ashley moves in with her two friends she breaks their bathroom mirror with a hairdryer. Later on in the movie, in the scene where her two friends are giving her a pep talk about luck, we see the same bathroom mirror in the background, which is now perfectly fine. Right after that, Ashley goes into the bathroom and looks at herself in the mirror, which has suddenly gone back to being broken.
Continuity mistake: In the scene where Larry's partner is writing on the white board, a line appears and disappears from the restaurant name Macelli's in the middle to the restaurant name Macelli's on the right side.
Continuity mistake: During the scene when Matt Dillon and Kate Hudson are talking on the porch, her bra straps move back and forth on her shoulders.
Continuity mistake: When Zach is getting ready for his date with Amy, Zack's beard length changes from a "five o'clock shadow", to a full beard, back to a "five o'clock shadow", between three shots.
Continuity mistake: When Harold first meets Ana there is a floury handprint on the front of her apron (on her chest) that disappears and then reappears.
Continuity mistake: When Madea is in the car coming back from court, Nikki smarts off at her and Madea turns around to hit on her. While this is going on, you hear brakes squealing and the driver is moving the wheel like the car is out of control. Yet, the background never changes, stays level throughout this scene.
Continuity mistake: Cecilia and Raymond are on the end of the dock and Raymond turns around and runs. Cecilia then says her line, turns around and runs. In the next shot the two girls are running towards the end of the dock. You can see Raymond running towards them but Cecilia is gone. She should be in the scene running the same way. (01:28:05)
Continuity mistake: When Cameron Diaz and Jude Law are in bed for the last time, her bra strap changes from being up and hanging down whenever the camera changes.
Continuity mistake: When Jerry and the Dr. are talking in the tent the first night on the way to the mountain, the Dr. shows Jerry a notebook with a picture of his wife and son. Jerry hands the notebook back twice in a repeat of the same shot.
Continuity mistake: In the scene where Gray has just come in to see the mother of her dead fiance's son in the house, the boy is throwing things everywhere. He stops by the TV and begins to pull CDs from the shelves into the floor. He pulls all the CDs off the shelves, but every time it cuts back to him, there are plenty more CDs for him to pull down.
Continuity mistake: In the scene where Viola meets up with Justin at the carnival, in one shot Justin's right collar is flapped down, in the next shot it is up.
Continuity mistake: After Max takes a bite of the tomato, the stain on his shirt decreases significantly after just a few shots. (00:18:05)
Continuity mistake: When Denzel Washington is taking off his clothes to be sent back in time. We see him take off his blue shirt. The shot then changes to look at the other guy and we see him take off his shirt again.
Continuity mistake: When all of the dancers are preparing for the showcase dance, Nora walks in with hair that has her usual bounce. When she and Lucy are talking in front of the mirror, her hair is almost completely straight, sporting just a few slight waves. When Tyler approaches her backstage, her hair is extra curly. It has only been a few minutes, and there was not enough time for her to have curled it. This is confirmed in the commentary.
Continuity mistake: When Paula has just shot the guy in the back while playing paintball, the next scene shows her walking toward the three guys and it looks like she still has her paintball attire on. In the next shot, it shows her close-up and she has a tank top on.
Continuity mistake: In the scene on the roof after the power transfer, Hannah falls through the sky light and Matt yells down to her. You can tell the close-ups on Matt were re-shot because Matt's hair is longer and styled differently in between shots.
Continuity mistake: In the first 'Ice Age' Diego isn't afraid of water (in the beginning he chases the woman and the baby through the river before she jumps off the waterfall and never shows any fear) but in this one he suddenly is. It's not like that he is just afraid of swimming because in the second movie he shows fear anytime when he touches water.