When Michael goes to David Wallace's house and asks if he can come in, David says "I'm just having lunch". Later on, however, David's wife is in front of the microwave, which says it is 9:25.
When Michael and David are in the jacuzzi, David is switching between holding a beer and having his hands underwater. In the beginning (16:46), his hands are underwater, then he holds a beer against his cheek (16:48), until it suddenly disappears again (17:17).
In the Sabre promo video shown to the Dunder Mifflin staff, Sabre boss, Joe Bennet, has no accent. The accent later appears in the video conference she has with Michael Scott.
(7:00) Gabe says that the IT guy is at the individual desks installing a site blocker. Long before 2010, this would be done at the IT infrastructure level through routers, not through the individual computers.