Making Gold Out of Nothing
It has been revealed that the pilot may have cost as little as $85 to shoot, being made out of two simple camcorders to film a 'day in the life' of Charlie Day, Glenn Howerton, and Rob McElhenney. The budget went almost solely to tapes for the cameras, which you can see in the low quality of the episode.
Creator/star Rob McElhenney and co-star Kaitlin Olson were married in September of 2008. This puts their wedding at around the same time as the air date for the beginning of the fourth season of "Always Sunny." They have two children, ages 2 and 4.
Just a Bunch of Jerks
According to Glenn Howerton, the show was originally to be about struggling actors in LA under the working title "Jerks". It seems like the theme stuck around for the actual show.