In a way, the annual Arrowverse crossovers are almost like TV movies. They span around two hours (sometimes more) of air time and feature epic battle sequences and impressive special effects. Some fans even argue they are better than actual DC Extended Universe films.However, despite their similarities to movies, there is little-to-no chance of them being released as a movie on Blu-ray or digital.RELATED: Knowing Oliver Queen's Fate Makes Arrow Season 8 BetterAsked if the upcoming "Crisis on Infinite Earths" crossover will be released as a movie on Blu-ray, Arrow co-creator Marc Guggenheim tweeted that, while he would love to do that, "Unfortunately, union regulations make it impossible. It’s very frustrating."

"Crisis on Infinite Earths" will be the sixth official crossover for the Arrowverse. Previous crossovers include "Flash vs. Arrow/The Brave and the Bold," "Legends of Today/Legends of Yesterday," "Invasion!," "Crisis on Earth-X" and "Elseworlds."

"Crisis on Infinite Earths" begins Sunday, December 8 at 8 pm ET/PT on Supergirl, then continues in Batwoman on Monday, December 8 at 8 pm ET/PT and in The Flash on Tuesday, December 10 at 8 pm ET/PT. After the winter hiatus, the crossover will conclude on Tuesday, January 14 in Arrow at 8 pm ET/PT and in DC's Legends of Tomorrow at 9 pm ET/PT.

KEEP READING: Crisis on Infinite Earths: Legends of Tomorrow's Jonah Hex Joins the Fray