Episode #1.1 - S1-E1
Continuity mistake: When Mark got into his cell, the top bunk had a vinyl-like covered mattress (or folded gym mat) that had a lengthwise seam along the middle of the side. He was not fixing his bunk bed while he was talking to cellmate Bernard, but when he was removing items from his bag on top of the bunk bed, it was now covered with a blue blanket and a sheet folded down by the pillow could be seen. A little later, the blanket was also covering the foot of the bed. (00:13:15 - 00:15:03)
Episode #1.1 - S1-E1
Continuity mistake: Mark's bunk bed has a blue blanket on it, but when Bernard is having a panic attack, Mark's blanket (and sheet) are gray. (00:15:03 - 00:16:50)
Episode #1.1 - S1-E1
Continuity mistake: The night Bernard got back to the cell, a view inside is backwards - the bed is on the opposite side of the window, followed by a close-up shot of Mark sleeping with the bed on the right side. (00:41:31 - 00:43:56)