Stupidity: Why didn't they take out the crushed hand guy while the creature was fumbling inside the glove? Plenty of time to do it. Why did no one use a knife to stab the creature?
Stupidity: While Mr. Butler was upstairs taking a shower, Lucas goes into his house, kills his wife, and takes the baby to the school (into Mr. Butler's classroom). Lucas wanted to take away Mr. Butler's family, so all he needed to do was also kill the baby at the house (or leave the dead baby outside on the porch for Mr. Butler to panic while searching). Lucas could have left the house without getting caught for committing a double murder; instead, he keeps the baby alive and assumes Mr. Butler will know he took the baby to his classroom. (01:17:53)