Plot hole: There is no reason for the prison guards to use portable computers in full view of the inmates to input the sonic deadline code. The guards can walk outside of the deadline whenever they need to input the code, or radio the guard on the outside to lower and raise the deadline like they do when bringing the workers out. In fact, this plot hole is compounded by the presence of the guards stationed outside of the deadline with their own computer, which makes the guard inside the deadline completely unnecessary. The interior guard is only there so Weiss has a way to get both the code and a computer, but this prison set-up makes absolutely no sense.
Continuity mistake: When Killian is looking through the computer for the next contestant, the last person they show is Mackenzie Spike. We see his personal info (occupation, hobbies, eye color, resident), the numbers pop up, and then it shows a completely different set of personal info (despite being the same guy with the same prisoner number).
Continuity mistake: When Buzzsaw runs by Richards, cutting the pipe in half, he has the chainsaw on his left hand. The camera watches Buzzsaw turn around, and you don't see the chainsaw, as the rider's left hand is on the handlebar, controlling the turn. The camera cuts to Richards for a second, then back, and the saw is on Buzzsaw's hand again.
Plot hole: After Richards goes back to his brother's apartment, he is somehow able to shower, shave off his beard and change his clothes despite the fact that the apartment is now occupied by a woman living by herself who would not have any reason to have men's clothes or male grooming products there.
Other mistake: The list of possible prisoners contestants the computer goes through shows different information, but the page with the 8 rows of double letters and numbers remains relatively the same, even though it's suppose to show variations and different information (i.e. AA always has -583 and -5483 and BB always has -484 and -4838).