Launch Party - S4-E3
Factual error: Michael and Jim are driving from their Scranton, Pennsylvania office to the company's headquarters in New York City for a website Launch Party. However, during the drive, it is clear by looking out the car windows at the mountainous and desert landscape that they are in California, where the show was largely filmed, and not in Pennsylvania, which does not remotely resemble that type of geography.
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.