Revealing mistake: When Toby announces that he's moving to Costa Rica, he gets up and goes to hop the fence. He moves out of frame and when the camera goes back to him, he's been replaced by a stunt double, which can be seen as the double's face is visible after he's scaled the fence. (00:17:15)
Revealing mistake: When Oscar is talking to the camera crew, and Kevin appears with his ice-cream falling, you can see his thumb having pushed the ice-cream scoop off the cone.
Revealing mistake: Ryan is seen on the left side of the screen breaking character by laughing and smiling, before seeing the camera and stopping. (00:18:05)
Revealing mistake: Michael is on his computer trying to open up PowerPoint in front of everyone in the conference room. He says "what we have to do here is go to run" and he clicks the run icon. However on Windows XP (the version he is using) and all other versions of Windows, clicking "Run" would open a separate window where you would type the name of the program. However, what appears on screen is a context menu as if he had clicked the "All Programs" button. You can even see the highlighted "All programs" button indicating that it was actually pressed. They likely had a PowerPoint presentation running in full screen with screenshots of a Windows desktop on each slide. As Steve clicked arbitrarily on the screen, it would trigger the next slide to appear thus creating the illusion that he was interacting with the operating system. (00:19:16)
The Target - S9-E8
Revealing mistake: When Angela asks Dwight to meet in their old spot, she arrives to see him apparently naked. There is pixelation around his groin area, but you can still see that he's actually wearing flesh-coloured underwear. (00:18:05)
Launch Party - S4-E3
Revealing mistake: In the first scene, everyone is in the conference room, just waiting for the block on the TV to hit a corner while Michael is blabbing away. The screen has no reflections, but later when Michael talks to the camera there is a reflection. In the scene you can also see the off shading on the characters in it, making it very apparent that the scene was filmed using a green screen.
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.