In the final scene, the gang records the end of the commercial. Zack's point to the camera is not in sync with the others. A few moments later, when they look at the tape, all three points are in sync. Brandon Tartikoff's hand actions during filming are different than the recorded version.
While filming the end of the commercial, Brandon Tartikoff is sitting on the desk, and Zack, Kelly and the rest walk up into camera view towards Tartikoff. When the finished version airs, Zack is on the desk speaking when the group, including Tartikoff, walks up to the desk.
The anti-drug Public Service Announcement is edited within a minute or two of shooting, and is immediately ready for viewing. In real life, editing would take much longer.