When Dean and Sam are talking with Jerry Panowski about a possible poltergeist, a co-worker walks by and says: "Poltergeist (1982)? I love that movie!" This comment was added in post and was not stated during filming.
Sam and Dean pose as Homeland Security agents: Jerry Wanek and Robert Singer. Robert Singer is one of the executive producers of the show and Jerry Wanek is the production designer. This was of course long before the character of Robert "Bobby" Singer was introduced.
Sam tells Dean to say God's name in Latin, "Christo", just as Dean is about to find out if Amanda has the demon in her. "Christo" is actually Greek, not Latin, for "Anointed One". If they wanted to be right they should have said "Christus".
When told about the plane crashing near Nazareth, Dean makes a comment about the irony of it. The pilot who crashed the plane was trying to get over his fear of flying after surviving a plane crash. His facing his fear by flying again could be described as "hair of the dog that bit him." Hair of the dog is a well known song by the rock group Nazareth.
First occasion where the boys wear suits as a disguise, to gain access to a crime scene. In this case, they wear all black suits and pretend to be Homeland Security with fake ID's, but the suits later become known as "the Fed Threads."