Season 1 originally had 10 episodes, but after seeing the cuts for episodes 3 and 4, the producers decided to merge them into one single episode and then use the cliffhanger for the second to last episode as the season finale, then using parts of the original season finale through the whole season. Hence making the season's 8th episode long.
Gillian Anderson and Kristin Chenoweth chose not to return to the show in season 2 in solidarity with creators Bryan Fuller and Michael Green after they were fired. Anderson was replaced by Kahyun Kim and the role renamed New Media, and Chenoweth's role as Easter was simply not mentioned again.
The character of Vulcan was not in the source novel; he is a new addition to the TV adaptation. The character is based on the ancient Roman god of fire, the forge, and metalworking, but the inspiration for the new character did not come directly from ancient mythology. Instead, the idea came from a story that Neil Gaiman told showrunners Bryan Fuller and Michael Green about traveling through Birmingham, Alabama, and seeing the 56-foot-tall cast-iron statue of Vulcan that overlooks the city on Red Mountain. In an Entertainment Weekly interview, Green said that Gaiman was told that during Birmingham's heyday as a steel town, one steel mill had had a policy that it was cheaper for them to pay restitutional damages to the families of workers killed on the job rather than to pay to ensure their safety. The "torch" in Vulcan's hand would light up one of three colors to communicate the safety of the Mills - a green torch indicated that no employees had been injured during the previous 24 hours, a white torch indicated minor injuries and a red torch signaled there had been a fatality in the previous 24 hours. Green said that Gaiman characterized that policy as "as modern a definition of sacrifice as there might be".
Nicolas Cage was approached to play the role of Mr Wednesday but turned it down, despite liking the script. He cited the commitment of doing a TV show as the main reason for turning it down.