Stupidity: After Dexter tells Hannah that the U.S. Marshals have distributed her picture everywhere, she questions how she will be able to flee Miami for Argentina. Dexter reasons he and Harrison can leave with her because the authorities won't be looking for a woman traveling with her "husband and child." It doesn't matter who she is or isn't traveling with. If the authorities have shared her picture, she's going to be flagged when she goes through security at the airport, which Dexter should certainly know. This is made all the more egregious when she takes Harrison to the hospital later in the episode and is ID'd by the receptionist.
Hear Today, Gone Tomorrow/Double Whammy/Autopsy Turvy - S1-E13
Stupidity: Double Whammy: Flippy shoots water into Nutty's mouth with the water gun, but instead of spitting the water out or swallowing it, Nutty keeps the water in his mouth as Flippy shoots more and more into it until he explodes. (00:12:25)