When the gang arrives at Alan's home office there's a wide shot as Alan's chair swivels. It clearly shows a 4 leg executive chair mounted on a swivel with a separate base. The executive chair's legs don't touch the floor.
When the gang enters Alan outer office, a shadow of the boom mic can be seen on the hallway door.
It had been established in previous episodes that the writers had worked for Alan Brady for at least a decade at this point, and that they occasionally socialized. It is untenable that Mel would have to explain to the others that Alan's wife is named Margaret, not Lillian.
Rob tells Laura he has torn his shirt. Laura cannot see Rob, but she replies--correctly--that the sleeve is the part that's torn.