Two episodes in the first season/mid-season replacement show a production studio room on the floor. For the rest of the series, the room is never seen again nor even mentioned as if it never existed.
In one episode, Bill is nervous about eventually dying in year 2032 (which is 36 years after the event) as if he never thinks of dying. Yet, later when his sudden death (from a heart attack) happens, it reveals he thoughtfully kept letters to be addressed to his co-workers --in case of the event.
When it's discovered that Dave was born in Canada, he says that he barely remembers living there because his family moved to Wisconsin when he was 5.
Bill's birthday is inconsistent from the mentions of it in at least two episodes.
Matthew's age is inconsistent with the mentions of his age or birthdate throughout the series.
Dave mentions a few times that he hails from Wisconsin. Then later in an episode it gets revealed (from his found birth certificate) that he was born in Canada. Yet, later Wisconsin keeps getting mentioned with him as if the episode never happened or the characters have all forgotten.