One critter notices that a cornered human has a gun. The other remarks "So what? and is promptly blown to bits. Followed by a (subtitled) Precision F-Strike as the first critter runs away.
In the fourth movie, the surviving protagonists have to escape the ship before it explodes. The AI, which thus far has not demonstrated itself as being terribly competent, provides a helpful countdown, only to interrupt the countdown by replying to something said to it. When the computer resumes where it left off on the countdown, the ship promptly explodes with seconds left on the clock. Turns out, Talking is not a free action.
Crowning Moment of Heartwarming: When Charlie makes a sacrificial dive in the second film to save the town, Ug temporarily morphs his head into Charlie's in tribute.
High Octane Nightmare Fuel: There's something terrifying about small creatures that can eat 20 times their weight, move very fast, jump high, are extremely strong for their size, and are highly aggressive. Also the fate of the Captain in the fourth movie where a baby Critter jumps in his mouth and bites at the back of his throat.