Dirty Harry - S4-E5
Continuity mistake: When Dexter listens to Officer Lundy's tape recording, we hear Lundy say that the Trinity killer's weight is 190 to 200 pounds. When we saw him recording that, he said 200 to 220 pounds.
Revealing mistake: When the Capri crashes into the goal net & they go to arrest the suspect you can see sky satellite dishes on the houses in front of them. Satellite TV didn't start in the UK until the 80s.
Revealing mistake: In the scene after the fire, when Kyle is playing with a candle, as he picks up the candle his belly button is visible. It has been established that Kyle has no belly button, therefore this is a mistake.
Continuity mistake: During the test. Light's collar is tucked in his shirt, but a few seconds later it is out.
Continuity mistake: Just before the robbery, Jake throws some water bottles and a flashlight over a small mound into the bushes, to hide them from the thieves. But when Mimi later picks them up, they are much closer to the truck, and on the other side of the mound. In fact, the bottles and flashlight would have been in plain sight for the robbers where she picks them up.
In Too Deep - S5-E8
Plot hole: Carter is apparently just learning about Feynman's Day, which Allison explains as "Eureka's version of April Fool's Day." It's highly improbable that Carter could have lived in Eureka for five years and still be oblivious of this, especially given all of the hijinks that happen.
Tomorrow's So Far Away - S1-E3
Continuity mistake: At the end when Hannah is sitting talking to Caroline's headstone, when the shots change from filming her from the right to the left, the wind is different blowing her hair in one and not the other.