1.First off, you can see the George Foreman grill that Michael burns his foot on — because he likes to wake up to the smell of bacon — in the episode "Dinner Party."
2.You know the teapot Jim gives Pam for Christmas? She uses it later in the Finer Things Club.
3.The lawyer Michael hires in Season 2 is the same lawyer Michael mentions when he and Dwight throw a watermelon off the roof and it hits a car in Season 3.
4.You could definitely already know this one, but it's amazing. Michael's girlfriend Carol — who broke up with him because he photoshopped himself into pictures of her family — has a tiny cameo in Threat Level Midnight. She's the Realtor of the real-life house Michael Scarn lives in.
5.Dwight and Kevin absolutely love fireworks in Season 2, and they're outraged by a potential lack of firecrackers in Season 6.