Jaynestown - S1-E4
Continuity mistake: When the foreman first slaps Simon on the back, the muddy handprint has quite identifiable finger marks, but in the next shot, when Simon is walking away, the muddy shape has changed. In a subsequent shot, the mudprint has disappeared entirely. (00:04:25 - 00:06:00)
Safety First/Crime Sheen Investigation - S1-E12
Other mistake: During Crime Scene Investigation, Jimmy explains his costume to Carl and, while saying "Sherlock Holmes", his chin goes into his jacket. (00:14:38)