There is an hour of unaired footage from "The Departure" episode floating around the internet. The episode was originally 2 hours long, but at the last minute the WB network would only give Roswell a regular hour-long slot, so they had to cut an hour of footage to make the episode fit into the time slot.
Fox was originally going to air the series but decided at the last minute not to air it. The WB Network bought the rights instead, but didn't like the original "Pilot" episode, so they made them re-shoot parts of it. That means that there is an unaired, original "Pilot" episode, and it is floating around the Internet.
Fearing cancellation during the show's first season, fans of Roswell sent tiny bottles of Tabasco sauce (the choice condiment of the show's aliens) to the WB network as part of a campaign to save the show. Roswell was subsequently moved to a new night and time and renewed for a second season.
Katherine Heigl tested for all three female leads before landing the part of Isabel Evans. Before winning the role of Maria DeLuca, Majandra Delfino originally auditioned for the part of Liz, which eventually went to Shiri Appleby who, like Heigl, tested for all three female lead roles, winning the lead of Liz Parker after several callbacks.
Throughout the series, various characters joke about growing up to work in the "Cheese Factory" (most notably in Season 1, "Monsters"). In reality, Roswell is home to a major manufacturing plant of Leprino Foods, the world's largest producer of mozzarella.
Similarities between Katherine Heigl's characters in Roswell (1999) and Grey's Anatomy (2005): in each her character, Isabel/Isobel talks to and dances with a dead lover, is extremely fussy about the holidays, and dates a guy named Alex.
In the third season episode "Secrets and Lies," after doing terribly on an audition for Star Trek: Enterprise (2001), Max's agent tells him that "There's still 'Buffy'," a reference to Jason Behr's guest appearance as Ford in Buffy the Vampire Slayer (1997). Also, Julie Benz, Who plays Agent Kathleen Tapolsky, played Darla on Buffy and Keith Szarabajka, who played Dan Lubetkin in "To Serve and Protect" and "We are Family" went on to play Daniel Holtz in eleven episodes of _"Angel" (1999)_ (gv).
The mountain where alien-children came from (and frequently go back to) is the same as the mountain Captain Kirk climbs in an episode of Star Trek (1966); it was also used in Bill & Ted's Bogus Journey (1991), as the mountain to which Bill & Ted are brought to be killed by the evil robots and in _Fastlane (2002)_ where Van and Deq go to meet with an arms dealer (and their car is shot with a rocket launcher).
Executive producer Jonathan Frakes appears on-screen near the end of the first episode. He is the man on stage that announces the crash of the UFO. He appears twice more as himself, once as a guest speaker in the season one episode "The Convention," and another in the season three episode "Secrets and Lies" where he holds a casting audition for Max on the show Star Trek: Enterprise (2001).
Though the name given to the alien Nasedo is purported on the show to be an Indian word for "visitor," it was actually made up by show co-executive producer and writer Thania St. John by scrambling the letters of the town of Sedona, Arizona.
Jason Dohring (Jerry), Kristoffer Polaha (Eric Hughes) and Jason Behr (Max) have all worked with Sarah Michelle Gellar in one thing or another. Jason Dohring and Kristoffer have worked with her one 'Ringer' and Jason Behr worked with her on 'The Grudge'. Kristoffer has also worked with Shiri Appleby (Liz) in 'Life Unexpected'.
On the TV show "The Adventures Of Rin-Tin-Tin", EP#1.31 "Bounty Hunters" 5-13-1955, Lt. Rip Masters scales a jutting rock formation. 45 years later, this same location would serve as an integral part of the "Roswell" TV show, housing the Pod Chamber and Granolith room.
Actors Brenden Fehr (Michael Guerin) and Adam Rodriguez (Jesse Ramirez) have gone on to work together again on the show The Night Shift (2014) as the characters Dr. Drew Alister and Dr. Joey Chavez, respectively. As with in this show, on The Night Shift, only Fehr's character appears in season one with both Fehr and Rodriguez's characters appearing in later seasons.