A commonly brought up plothole is that Buzz acts like a toy when people are around despite being under the impression that he is a Space Ranger. Why would he do that? My idea is that he was trained to do so. I'm not an expert on special forces but it would make sense for them to be trained to act like the locals in order to stay safe (the locals would be aware of dangers they aren't) and to remain undetected (they could pretend they know the local customs so potential threats won't notice a stranger and attack). Therefore, I would argue that is simply what Buzz did. He didn't know that remaining still doesn't prevent you from getting eaten or something, so it would make sense for him to act like a toy despite not knowing he is one.

Edit: I've replied to a couple of comments elaborating my idea on one part of this, so I thought I'd put it up here for easy reading. Apparently the instinct to play dead is hardwired into the toys brains either as part of a trade off from what gives them life or for some other reason. Additionally it is supposed to be overrideable but only with difficulty. At first I thought this would end my theory because the moments when toys fight this aren't very long, e.g. scaring Sid, winking in Andy's arms etc. However I realised (or I think I did) that the toys can act near humans indefinitely and without compulsion to stop.

My first part comes from the bit in Pizza Planet where Buzz and Woody run through the restaurant to get to Andy They are constantly near humans yet do not stop being animate. You could argue that they are hidden for most of this time so wouldn't stop moving anyway which brings me onto my next point. In Toy Story 2, part of the gang crosses the road in front of Al's Toy Barn causing a pile up. If they were compelled to act like toys to avoid humans noticing them then this would have been impossible. Equally, the override has nothing to do with danger or the toys Sid was about to explode would run away. Instead they follow the protocol until death. Therefore I would say that the biggest cause of toys acting like toys is their decision to do so, as there does not appear to be consistent proof otherwise, meaning that someone who didn't know they were a toy (Buzz) wouldn't act like that inherently because they were a toy but because they consciously believed they should do so (in this case as a result of his training).

TL;DR: There is enough free will involved in acting like a toy for the theory to make sense.