During the incinerator scene Slinky Dog is first pulled to the ceiling, realizing its because of a magnet the other toys grab metal objects to get pulled up and escape the grinder. On the other side of the grinder the toys release the metal objects and fall back to the conveyor belt, inexplicably Slinky is there with them and the magnet seems to no longer affect him.
When Andy is introducing his toys to Bonnie, he introduces Jessie. In Toy Story 2 when Jessie came to live with Andy he gave her the name "Bazooka Jane". However, he gives her that name before using her pull string. The message "My name is Jessie, pleased to meet you" is featured on the toy and so Andy had a few years to pull the string and learn her real name. Furthermore, it could've simply been a nickname that he gave her, similar to how he calls Mr. Potato Head "One Eyed Bart" and Hamm "Evil Dr. Porkchop".
When Lotso removes Mrs. Potato Head's mouth, she is unable to use it. This might contradict many other instances in which the Potato Heads are able to use their body parts when not connected to their body, but it seems that Lotso is also squeezing Mrs. Potato Head's lips together to impede her speech.
After Molly destroys the bridge, and Andy says "Run for your lives" to the camera, Mr. Potato Head has both eyes, despite being shown seconds earlier as One Eyed Bart.
When "demo" Buzz escapes from under Rex and Hamm, and is running to get away from the toys, he opens his left arm to call out to Star Command, saying he is being held captive by his own prisoners. When Buzz thought he was the real Buzz Lightyear (in Toy Story), he always pressed the red button on the right side of his chest to call for Star Command.
Lotso pleads for help in the compactor scene. When we see his arm rise from the trash, the platform is moving towards the compactor. The camera switches back to Woody who is trying to make a decision. When we switch back to Lotso, the platform appears to be moving away from where the compactor is, backwards. This effect of an apparent change in direction is caused by the fact that the magnet strip above is moving faster than the garbage platform below,as can be seen in previous scenes.
The toys never let people know they are alive, but several escape attempts, patrols by Lotso's gang and other things are recorded by the security cameras at the day care center. It is possible to alter images seen on security cameras, and conceivable that one or more of the toys in Lotso's gang would know how.
When the toys are taken to the curb to be picked up by the garbage truck, there are three garbage bags. When the garbage man picks up the bags, there are only two. Andy puts the toys in the 3rd bag and when woody splits open the 2 remaining bags they are full of garbage so are obviously not the bag with the toys in. The toys must take the 3rd bag with them during the escape.
When Woody is taking away by Bonnie, she puts him in her backpack and Woody is unable to open the zipper to escape. When Bonnie brings Woody to Sunnyside, Woody unzips her backpack fine. However Woody doesn't try to unzip her backpack in the film.
When the "caterpillar room" children go outside for recess, the clock shows 3:00; when they return to the room for Andy's toys' first playtime, the clock shows 1:00.
When Barbie removes the screws from Buzz's back and they reset him they rush to escape and never reinstall the screws but his cover stays closed.
The Wild West train locomotive's motion wheels have been stopped by Woody in opening scene, but are shown running in a short time later (in two different sequences).
When the children charge into the Caterpillar Room and grab the toys for the first time, Rex is immediately seen smeared with paint, before the paints come out.
Throughout the movie, Mrs Potato Head is missing her right eye and complains that it was left "somewhere dark, and dusty". Later, when Mr Potato Head escapes from 'The Box', he is able to manoeuvre all of his parts to the tortilla, including his eyes. Since Mrs Potato Head is essentially made from the same moulds as Mr Potato Head, she should have been able to manoeuvre her eye out of the dark.
There's an assistant in the Caterpillar Room at Sunnyside, so why did she not realize that Andy's toys were not suitable for the toddlers and not supposed to be in there?
Near the beginning of the film, in Andy's room, the bottom dresser drawer is left partly open. It is never closed by anyone in the scenes, but is shown a short time later completely closed.
Andy is giving his toys to Bonnie. He shows her the three aliens from Pizza Planet. All three are facing her but when Andy puts them down in front of her, they suddenly change direction to be facing Andy.
After Buzz dances around Jessie in the shrubbery, Woody and the others run towards the garbage chute. Meanwhile, Buzz stands in the background against the barbed wire fence. Parts of the fence have been animated in front of him despite the fact his body is clearly standing in front of it.
During "Toy Story 2", Woody was refurbished, including having "ANDY" (with a backwards "N") that was written on the sole of his boot painted over. In this movie, "ANDY" is again written on his boot, again with a reversed "N". It's assumed that Andy rewrote it after he got back from camp. But being older than when he first got Woody, Andy would've written his name without the reversed "N".
After the opening sequence, we see the toy version of Mr Potato Head, with his left eye removed, portraying One-Eyed Bart inside a cardboard box. When his mother enters with the camera seconds later, Andy shows Potato Head and Woody to the camera and both of his eyes are in place.
During the opening train robbery sequence, the numerous trolls are seen as 'orphans'. Yet after the sequence is over, the trolls are nowhere to be seen, although all other characters seen in the sequence are present and accounted for.
Andy gives the toys to Bonnie, then later drives away from her house. We hear the car on its way along the road. He drives from left to right across the front of the house but when we see his car from the house, we see that the house is at the end of the road and the road is perpendicular to the front of the house.
The Post-Net bar code on the "State University" envelope (addressed to a Pixar office) which is moved out of the way by Woody to reveal the old photo, is not validly formatted.
When Mr Potato Head meets the other toys using his cucumber body, Bullseye rolls the plastic potato body towards him. The holes for his eyes, nose, ears and hat are visible but there is no arm or mouth hole.
Although Mr. Potato Head says Andy is seventeen years old, there's a picture of him in a graduation cap and gown on a bulletin board on his desk.