Stupidity: When Crowler goes into the chicken coop, he leaves the door to the coop wide open. Leaving the door open could have risked the chance of the chickens running out of the coop. (00:00:20)
Stupidity: Characters repeatedly make note of how hard to kill the Wraith are, but sometimes, especially in the final episode(s) of season 1, they go down easily in a few bullets each, and then don't even regenerate as the characters turn their attentions elsewhere.