Louie's apartment was completely destroyed by fire but the hallway just outside his door (and the the outside of the door) shows no signs of fire or smoke damage.
When Jim and Alex are in Louie's destroyed apartment. The scene where Alex tells Jim not to panic, as Jim is sitting down. After Jim jumps up screaming hugging Alex, right before commercial break you can see the shadow of the crew/equipment near the couch in the background on the white table.