Character mistake: Meredith admits during the ethics seminar that she has been sleeping with Bruce, the HammerMill rep, for discounts on paper/paper supplies for the company, as well as Outback steak coupons, for 6 years. But, Dunder Mifflin did not begin selling Hammer Mill products until 3-2 "The Convention" when Michael got the contract.
Character mistake: Carol says that Michael proposed to her on their fourth date. The proposal happened in Season 3, Episode 6, Diwali, and in that episode, Carol mentioned that it was their ninth date.
Character mistake: When it briefly shows the sign for their wedding rehearsal dinner, they spell Jim's last name wrong. The sign reads "Beesly-Halpret" wedding rehearsal dinner, not Halpert. (00:11:00)
Character mistake: Erin is shown drinking an espresso in 5-25 "Café Disco". Later in the series in this episode, when Clark brings an espresso machine in that was given to him by Jan, everyone decides to try every flavor. In an interview Erin starts rambling but then remember the actual question she was asked, have you ever had an espresso before, she said she had not.
The Meeting - S6-E2
Character mistake: When Dwight and Toby drive by Darryl's house to investigate his injury, a New York Yankees sign is on the front porch of Darryl's home. Throughout the show, however, it is strongly implied that Darryl is a Philadelphia Phillies fan. This is a character contradiction. (00:10:19)
Character mistake: In the scene where Ryan and Andy are taking a tour of Gabe's bedroom, Ryan says "Hey, Marantz tube stereo from the 1970s" It is in fact a Marantz SR 1000 stereo receiver. This model uses solid state electronics, not vacuum tubes. (00:13:30)
Weight Loss - S5-E1
Character mistake: Pam attends her first class and notices she is in the wrong class. Written on the whiteboard is the title of the course and the name of the teacher. While obscured, you can see it is supposed to say "Professor Monaghan." Written on the whiteboard is: "Proffe [obscured] ghan." Professor is spelled with one F. (00:09:05)
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.