According to Neil Gaiman, co-author Terry Pratchett's last request to him before his death in 2015 was for Neil to write the screen adaptation. Previous attempts to bring the book to television failed due to not being able to find a writer able to adapt the book while keeping its spirit and humor.
Terry Gilliam tried to adapt this as a movie several times over ten years before admitting defeat. He came closest in January of 2002 when he had Robin Williams on board to play Aziraphale, and Johnny Depp was signed up for the part of Crowley. He had raised fifty million dollars from investors and he just needed a Hollywood studio and a bit more money to start production. His confidence in the project was completely shattered when he found himself in a post 9/11 yet pre-Pirates of the Caribbean: The Curse of the Black Pearl (2003) Hollywood where every studio and producer he met told him the same thing: "nobody wants to see Johnny Depp movies".
Most music throughout the series is from Queen. This is a running joke in the source book, in which every cassette tape left in Crowley's car for a fortnight, magically turns into "The Best of Queen."
Adam's earthly father, Mr. Young, has the license plate number "510RAT" which reads "TARDIS" backward. The Tardis is the time traveling police box featured throughout Doctor Who (2005), a show in which many of the "Good Omens" cast has also starred or appeared, most prominently David Tennant in the title role from 2005-2010. This is one of numerous "Doctor Who" Easter eggs that appear throughout the series.
The show makers tried out various concepts for the title sequence: a puppet show performed by God, a medieval tapestry, a biblical manuscript.
The crew finally settled on a title sequence inspired by "Monty Python" animator Terry Gilliam's work.
The crew finally settled on a title sequence inspired by "Monty Python" animator Terry Gilliam's work.