
Revealing mistake: During the diner scene, there's a critter on top of a trash can, standing next to the wall. One can see the hole through which the puppeteer moves him.

Visible crew/equipment: When the Critters are in the restaurant, The Hungry Heffer, as the camera pans across some Critters eating lettuce and other food. If you look closely, you can see one of the puppeteers hands coming out of the bottom of a critter puppet. The puppeteer is wearing a dark shirt with what look like gloves.
Answer: From what I recall, Charlie followed the bounty hunters as they walked away in the first film. So the implication is that they decided to let him tag along with them. (And that makes sense. After all, he helped them destroy the Krites in the first film, so he'd be useful.)
TedStixon