Actor Allusion: Matheson is gleeful at the beginning over someone named "Reynolds" retiring due to his wife's sickness. Mekhi Phifer played Ben Reynolds in Lie to Me.
Executive Meddling: Bill Pullman mentioned in an interview that Oswald Danes ended up dying because the lawyers said so. Not that we can blame them, but still.
Fan Nickname: "The Triangle", because of the revolving triangle that appears on the cellphones of their lackeys. Those who have read the brief Starz synopses for later episodes knew they were called the Three Families, however.
Recycled Set: Scenes filmed at Ontario International Airport are set in airports in Los Angeles, Shanghai and Buenos Aires.
Troubled Production: While production wasn't a complete trainwreck by any means, there were nonetheless a few problems along the way. Firstly, Starz demanded an increase in the number of episodes from 6 to 13, eventually resulting in 10 episodes being decided on as a compromise. Then, Russell T. Davies' partner was diagnosed with cancer, forcing Davies to spend time away from the production and eventually hand over showrunning duties to Jane Espenson. Filming was less problematic, but Bharat Nalluri, who was intended to be the lead director for the series, ended up quitting after just one episode, resulting in a bunch of different directors working on the show over the course of the season.
What Could Have Been: Miracle Day was come upon after the series creator Russell T. Davies found his efforts to sell the format rights to the major American networks were hitting a brick wall. Davies wanted to retain continuity ties to the British series, including John Barrowman in the lead role, whereas most of the people he was in talks with at the networks suggested remaking the show wholesale for American audiences, including recasting all of the lead roles, as well as downplaying/dropping Jack's omnisexuality (details vary on the full extent of this). Davies eventually found Starz Entertainment, who were the only guys that were happy to make a true co-production to Davies' specifications.