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.