From start to finish, the entire production used a total of three Argentinian horned frogs to play the "red frog". ("His" eyes very obviously change color from bright red to a more neutral color.)
The Comic Book that Mason is reading in a number of episodes are each editions of "Cosmic Plan", a subtle nod to the role of the reapers.
While Rube's cause of death is never overtly stated, Season 2 episodes strongly imply that on the night he was killed, Rube attempted to rob a bank. (Examples: the wanted poster Rube finds when searching for information about Rosie and the gun he carries around in his flashbacks).
The drum kit that Reggie owns is made by Ayotte, a Canadian drum manufacturer.
The actors who play the versions of George and Mason (seen in the pilot) that regular people see are credited as "Un-George" and "Un-Mason", respectively.
Inspired by the Piers Anthony novel On A Pale Horse. Unlike in the novel, the series shows multiple Grim Reapers working the planet, as opposed to just one.
The red frog that keeps appearing here and there through the series comes from the first scene of the pilot. It is, depending on who you ask, the first "person" to die, the first reaper, or both. The frog is an Argentinian horned frog (aka, "the Pac-Man frog"), which does not make sounds like North American frogs (during one take, however, the frog hissed when Ellen picked it up, scaring the daylights out of Callum Blue and Jasmine Guy), The "frog sound effect" is dubbed in. The Pac-Man frog also has sharp teeth, and should only be handled by professionals, as its bite is very painful.
Although set in Seattle, the series is actually filmed in Vancouver, B.C., Canada. No effort is made to hide street signs, local business names (e.g., Avalon Dairies), etc., and in one episode both a Canadian flag and a B.C. flag are visible in the background.
According to Bryan Fuller (the show's creator and head writer for the first four episodes), it was originally planned that George's father would be gay, and this development would spell the end of Clancy and Joy's marriage. After Fuller left the show, the show's new executives decided that Clancy should be heterosexual, but philandering with his female students.
The pilot took one month to film, whereas all other episodes were filmed one per week.
Elias Toufexis, who played Brian in the episode Last Call, would go on to voice Adam Jensen.
Screwed by the Network: The show's executive meddling caused the writer and team to split after three episodes.
Shares elements in common with the 1990 Film Soultaker but played as a dark comedy instead of a slasher film. also the focus is on the reapers more than the souls taken. however the rules appear to be the same for reaper and reapee alike.