The only time I think a director goofed was when Cullen was on Family Feud. After Fast Money, Bill, apparently not aware the cameras were still rolling, walked over to the center of the stage. I didn't see him limp, per se, but it was rather, a very stiff walk.
Bill was also seen walking briefly when the IGAS panel was told to walk across the street to the new theatre where IGAS was going to be taped. On that episode, the secret was that they were striking the set to be moved across the street, and that there was going to be a party at the new theatre. So, the panel was at their desk, alone, aside from cameramen and other staff. Garry instructs them to walk down the hall and across the street to the new theatre. So the cameras were following the panel, and Bill was seen walking with the panel, but the panel quickly realized what was going on and walked in front of Bill, then the camera following them only shot from the waist up.