Visible crew/equipment: Near the start of the episode when the FBI arrive at the house, two crew members are reflected in the car door as Agent Weller steps out.
Continuity mistake: The semi that is hooked up to the the trailer hauling the DEA guns is not the same semi that is hooked up to the trailer when it explodes.
Trivia: Since episode 10 of season 2, "Nor I, Nigel AKA Leg in Iron", all the episode names (at least to episode 21) are palindromes (a word or phase spelled the same forward or backwards).