(at around 58 mins) At the sing-off, when the Chipettes are singing, Ian uses his phone to make a video. He says "If you like what you see, call Ian Hawke...." however, when the video is seen on a website by some record executives, Ian says "If you're interested..."
(at around 10 mins) The Chipmunks were spinning in the the bowl on the food processor and they flew out, the phone rang and they answered it. Somehow in between the time they flew out and they answered the phone, the food processor is turned off, but nobody went back to it to turn it off.
(at around 58 mins) At the sing-off, when the Chipettes are singing, Ian uses his phone to make a video. At the end, he winks to his phone. However, when the video is seen on a website by some record executives, Ian does not wink.
(at around 1h 21 mins) At the end of the move, the Chipettes and Chipmunks say goodnight--all but Alvin, who then fusses with the lights with Dave. When Dave switches off, Alvin switches on, then Dave switches off. The camera switches back to Alvin and somehow the switch is "magically" switched back on.
(at around 39 mins) When Toby is breaking the drums, the same drum gets broken twice.
(at around 7 mins) The Chipmunks ride in the front passenger seat of the car and the seat belt is the kind that goes across the lap, but most front passenger seat belts go across the lap and shoulder.
Ian incorrectly refers to the Chipettes as "singing, female chipmunks"; following the conventional order of adjectives, the grammatically correct way to describe them would be "female, singing chipmunks".
(at around 5 mins) Jackie Seville referred to Toby Seville as her grandson, but he later (at around 47 mins) referred to her as his aunt. This was actually not a mistake because Toby was talking to Dave Seville at the time, and he was describing her from Dave's point of view.
(at around 1 min) At the beginning of the movie, a Mexico City audience is watching a live video feed of a performance in Paris. The Chipmunks then fly to Los Angeles on Global Pacific Airlines.
(at around 19 mins) When Ian takes the Chipettes to the roof they perform for him on the Jett Records sign. The sign at the very edge of the building facing the parking lot. As Ian sits on the roof and watches the girls, the sign can be clearly read, but as it is three dimensional made of stylized, cut-out chrome letters, it would be backwards when viewed from the street.
(at around 1h 9 mins) Alvin answers an iPhone by pressing a button on its touch screen. While talking, he keeps inadvertently touching the "End Call" button, but the phone does not hang up.
(at around 17 mins) The Chipettes' FedEx package doesn't have an address label on it.
(at around 30 mins) In Toby's high-school flashback, when he's playing dodgeball and admiring Julie, he closes his eyes and flinches just before getting hit in the head with a ball.
(at around 1h 9 mins) When Alvin answers a call from Brittany (she is using Ian's number), he doesn't turn speakerphone mode on (button on the screen is not lit), but still talks like he does.
(at around 24mins) Theodore's lips don't move when he says "Cut it out!"
(at around 1h 14 mins) When Ian is controlling the toy helicopter with the Chipmunks on it, he suddenly trips and the controller flies out of his hand. While in the air, it suddenly shrinks enough for one of the Chipmunks to catch it. Once one of the Chipmunks catches it, it is small enough to fit on Ian's fingertip.
At the beginning of the movie, Dave was wearing a tan shirt, a brown jacket, and blue jeans. But when he was talking to Toby on the phone, he was wearing a different pair of clothes. And then, his clothes changed again when he went to see the Chipmunks and the Chipettes perform at the end of the movie. Unless he actually brought a few pairs of clothes to Paris, he shouldn't have been able to change his clothes after his recovery.
(at around 1h 3 mins) The signage at the zoo entrance is "Los Angeles Zoo", but the signage inside the zoo reads "California State Zoo".
(at around 5 mins) Toby Seville is introduced as Jackie's "grandson". However, he refers to Jackie as "Aunt Jackie" when she's being loaded into the ambulance near the start of the movie.