Stupidity: When Mac and Lindsay are reconstructing the stab wound found on their victim on their pig specimen, a couple of the weapons they use are long, thin knives; since they obviously don't match the circular wound, Mac at the very least would know those could be excluded by default.
Stupidity: Jaden places a wet cloth on Blair's forehead. However, he places the cloth on top of Blair's fringe, instead of brushing it away, which would make it harder for the water to touch her skin. (00:03:02)