Continuity mistake: Andy states that he has a step-mother who is/was a secretary, but in all other references to Andy's father's wife she is Andy's biological mother.
The Manager and the Salesman - S6-E15
Continuity mistake: When Michael enters the room he messes with Jim's hair and Jim's hair is noticeably different, however a few different camera angles later Jim's hair is back to normal even though he couldn't have possibly had time to touch it. (00:09:10 - 00:09:50)
Continuity mistake: When Jim is outside comforting Pam after she finds out her mother is dating Michael, he begins to explain a mallard recording device that Dwight gave to him and used a big hand motion that put his hand in the air. In the next shot, the hand that was in the air is now gripping his coffee cup.
Double Date - S6-E8
Continuity mistake: In Fun Run (4-1) when Michael hits Meredith in the parking lot, it is said by him that it was on company property, but in this episode Pam says that the hit in the parking lot will be off company property.
Continuity mistake: When Dwight is talking to the kids, he picks up one fry. In the shot of him from behind, he's holding two fries. It goes back to one fry when he takes a bite.
Continuity mistake: When Kevin is writing Pam a check, he flips it open so the check register is folded under the checks. After he says "wait till Monday", the check register is no longer folded under the checks.
Continuity mistake: When Jim reveals the tiny desk underneath his "Quad-Desk" to Dwight, Dwight sets his briefcase down on a chair not shown in any previous shot. (00:21:05)
Happy Hour - S6-E20
Continuity mistake: When Michael is doing press-ups Angela is sat, then she stands to see what's going on - away from her chair, it cuts to another shot, and she is sat down again.
Continuity mistake: When Michael begins the conversation with Jo, the door behind him is closed. After a few lines, the door is open. (00:19:10)
Continuity mistake: When Jim and Michael are in the conference room with Jo, Michael messes up Jim's hair. A few shots of Jim later, his hair is nicely combed again.
Suggested correction: Michael didn't establish the contract with Hammer-mill. Rather, he locked them up as an exclusive supplier. It's unknown if they were already selling the products to Dunder Mifflin alongside Staples and Office Max.
Wrong, Josh says they cannot sell Hammer-mill products as they are exclusive to Staples so therefore they wouldn't have been able to sell there products alongside as mentioned before until Michael made them an exclusive to them solely, Dunder Mifflin. Therefore the original mistake stands true.