Other mistake: When Rex shakes the table causing the baby monitor to fall, the batteries fall out and we see the open battery compartment with markings for positive (+) and negative (-), and space for two AA batteries. Woody jumps off the bed and places the two batteries inside the compartment, but before he closes the compartment note the position of the battery closest to the top of the monitor. The positive side is actually where the negative side should be so the monitor should not work, but the monitor turns on just in time to hear the soldier's warning. (00:13:15)
Other mistake: While Sid's toys are working with Woody to get Scud out of the house, just as Hand-in-the-Box is holding the doorknob we can see the screw mounted on the latch's hasp below the loop - which really doesn't make any sense, but as Hand opens the door the screw has suddenly vanished from the hasp and is now properly mounted on the doorway's loop plate, where it's meant to be. If the screw were really mounted through the hasp, the door could not be opened.
Other mistake: There are six various bolts, locks, and latches on Sid's door above and below the doorknob, and some are in their locked positions when the door either opens or closes. For example, after Sid replaces the doll head with the pterodactyl head and calls Hannah, when the door opens we can see the dead bolt and slide latch are both slid out in their locked positions and yet Sid's able to open and shut the door, which is quite impossible.
Other mistake: It's been mentioned that Sid sets his clock for 8:25 and it goes off at 7:00. Here's some more errors for Sid's crazy clock physics. When Woody is saying "Psst" to Buzz from inside the blue plastic basket, the clock on the wall says 6:25, yet the alarm clock next to Buzz says 6:55. It goes off 5 minutes later and after Sid takes Buzz out of the room, the clock on the wall has changed to 3:10. When Woody is talking to Sid's toys a minute later, the clock now reads 10:00. The maximum amount of time that passed between the already wrong 3:10 and the 10:00 is 5 minutes. You can tell because Sid wanted to launch Buzz strapped to the rocket ASAP and Woody wanted to rescue Buzz from his current strapped-to-a-rocket state very fast. (00:56:45)
Other mistake: During the scenes in Andy's room, when characters are standing near the window beside Andy's bed, and also on both the interior and exterior sides of the window behind the desk, we can see the same markings/scratches/chipped paint on their white lower sash rails, though the marks on the exterior side of the window behind the desk, are actually opposite from the other marks.
Other mistake: After throwing Woody to the floor, Sid raises the window shade and tries to burn a hole in Woody's head by using a magnifying glass to focus the sunlight. Sid is leaning over Woody with his back toward the window and yet he does not cast a shadow on Woody. In addition, the position of Sid's body would block the sun's rays from hitting the magnifying glass but the close-up shows the narrow beam of light hitting Woody's head.