Continuity mistake: There's an electrical outlet on the wall below the window (aligned with the window shade's loop) in Sid's room near the Megadork poster, but when Sid throws Woody to the floor and raises the shade (before he scorches Woody's forehead with the magnifying glass), that outlet has vanished.
Continuity mistake: All the walls in Andy's room have white wainscoting with the cloud wallpaper on the upper part of the walls, but in the opening shot of the room we see behind the "saloon" box that the cloud wallpaper covers the wall all the way down to the baseboard. The tall dresser isn't where it should be as well. (00:00:40)
Continuity mistake: When Buzz is in Sid's sister's room, Woody comes up to it disguised in the Christmas lights. He then leaves them beside the door before he goes in. When they leave the room, the lights are gone. Later the lights return when Woody goes to get them, but there are fewer of them. (00:47:22)
Continuity mistake: When Rex and Mr. Potato head pop out of the moving box lots of packing foam pops out, yet later when the box spills out in the moving truck there is not any packing foam. (01:09:07)
Continuity mistake: When the army soldiers are yelling into the baby monitor that the kids are heading up to Andy's room, the baby monitor is right in front of Woody on the floor. Yet, when the camera pans out to show all the toys scrambling for their places the monitor is gone, and Hamm is right in front of Woody. Then, when the camera zooms back in to show Woody, the baby monitor has reappeared. (00:12:30)
Continuity mistake: Before Woody uses the remote control to have RC push Buzz off the desk, there are red, yellow, and blue pushpins in an empty area of the bulletin board, but after RC hits the bulletin board, in the closeup of the pushpins falling off those colors have changed to green, red, and yellow, with the green pushpin remaining in the empty space, but when the bulletin board starts to fall over that green pushpin is gone and it's back to the red, yellow, and blue pushpins.
Continuity mistake: In Andy's room, the general ("generil") store box under the crib near the closet door has a cow illustration on its right side, but in the next few shots there's a drawing of two windows on that side of the box, and then it keeps switching between the cow and two windows in following shots.
Continuity mistake: In Sid's room, there's a lightbulb hanging over the table (which he turns on when he switches the doll's and pterodactyl's heads), and its electrical cord that hangs beside the lava lamp (filled with toy heads) vanishes and reappears a few times during the scenes there.
Continuity mistake: After Woody tosses the string lights to Andy's toys at the window Mr. Potato Head hangs onto the end of it, but in the shot from behind Andy's toys when Woody's shaking Buzz's arm and imitating his voice, we see the outside of Sid's window and the string lights have vanished, then they reappear.
Continuity mistake: While Andy's falling asleep, when Potato Head and Rex pop out of the Eggman Mover's box it has "Andy's toys" written on one side and the adjacent side is solid - no openings, but when Woody opens this box in the moving truck, there are now open handle cutouts on the two adjacent sides to where "Andy's toys" is written.
Continuity mistake: When Buzz and Woody are attempting to enter the truck towards the end, they ride RC and grab a hold of Slinky to help pull them up. RC loses power and Slinky starts to be pulled onto the road. When he touches the floor to stop him falling he actually pushes against the flow of the road. (01:11:50)
Continuity mistake: Buzz, while pushing the tool box off of the blue basket Woody is in, stretches to about 3 times the length he normally could from that position. When he first starts pushing against the window sill with his feet, he stretches out fully a few seconds later, about half the length of Sid's desk. He continues to push the box over and says "Almost there..." before he does and we can see he still has his feet on the window sill. Most people will have to watch it for a better understanding. (00:59:37)
Continuity mistake: When Sid is setting the alarm clock, he sets it for about 8:25, when the alarm goes off the next morning, it's actually at 8:00. (00:55:42)