Originally, according to Creator Rob Thomas, Veronica and Duncan were going to be related. After it got picked up by UPN, a broadcast network, and not by HBO, Showtime, or FX, they decided not to push it into "Twin Peaks (1990) territory".
On March 13, 2013, cast members Kristen Bell, Jason Dohring, Enrico Colantoni, and Ryan Hansen, and show-runner Rob Thomas appeared in a video posted to the crowd-sourcing website Kickstarter that challenged fans of the television show (which had been cancelled in 2007) to pledge two million dollars to fund (or help fund) a feature film project based on the show. The project broke a Kickstarter record when it made more than one and a third million dollars in about six hours. The entire amount was raised and surpassed in under eleven hours, subsequently Veronica Mars (2014) was released.
Creator Rob Thomas said on the season three DVD extras that Ryan Hansen's character Dick Casablancas was not originally meant to be a series regular. He was first cast for the second episode, as a nameless, rich Neptune resident with one line ("Logan!"). Thomas said that they read many young actors for the line, and when it came down to a choice between Hansen or another actor, they cast Hansen purely because he had "good hair".
The network told Rob Thomas in advance that season three was probably going to be the last of the show, so he could have the opportunity to wrap up the series. Thomas got so angry at them that he wrote the season finale as an anti-finale. In retrospect, he has said he doesn't regret it because they could not have made the movie if the show had had a proper ending.
UPN, the network that aired this show, was concerned during early episodes that viewers would confuse Teddy Dunn and Jason Dohring, who play Duncan and Logan, respectively. A color code was created where Dunn wore blues, and Dohring wore earth tones (greens, browns, et cetera). The color code was maintained for the duration of the series.
In an attempt to keep the struggling show on the air after its third season, Creator Rob Thomas filmed an extended pitch for the fourth season that advances the show's timeline considerably. Instead of being a college undergraduate, as she was at the end of season three, in the speculative season four, Veronica has graduated from college and the F.B.I. Academy and is starting her first day as an F.B.I. Agent. The pitch contained a whole new cast of heretofore unseen characters, and, except for Veronica herself, none of the characters from the show's previous seasons. The CW failed to pick up this new version of "Veronica Mars", and the show was cancelled.
Concepts included in the original project notes for the show, that were later dropped, include Veronica being thirteen when Lilly was murdered, Keith being fired because of evidence disappearing from the police station, with hints that Don Lamb was behind it, Strom Jenkins, a character who called in the Abel Koontz tip, and Veronica finding that Strom Jenkins, Don Lamb, and Jake Kane were part of a larger conspiracy to cover up Lilly's death.
On March 29, 2006 a fake press release titled "Veronica Mars Canned" was released informing fans that the show had been cancelled. After a few hours, Creator Rob Thomas informed the fan base that he had been getting calls from the writers asking if they still had jobs, and the show had in fact not been cancelled.
In the original project notes, and the original pilot script for the show, there were some name changes. Lilly's name was Samantha, Lianne Mars' was Rebecca, then Abbie, Wallace's last name was Collier, Logan's last name was Hewitt, and the Kanes' last name was Cain, then Caine.
In the series, Lilly Kane (Amanda Seyfried) was murdered on October third. This date ironically coincides with the now iconic query from Lindsay Lohan in Mean Girls (2004) (also co-starring Seyfried) when she doesn't know the date. October third has since become the unofficial holiday "Mean Girls' Day".
In an episode, Veronica tells Wallace that she is thinking which Gilmore Girl he is. Teddy Dunn (Duncan Kane) appeared on Gilmore Girls (2000) on season four, episode twenty-one, "Last Week Fights, This Week Tights", and he is not the only one. Max Greenfield (Deputy Leo D'Amato) appeared on the show in season four, episode four, "Chicken or Beef?". Kristen Ritter (Gia Goodman) was a recurring character on season seven of Gilmore Girls (2000), where she played the role of Lucy.
In the later seasons of the show, Logan's swanky apartment has a large square window in the back, the design on the outer part of the window revealed the Silver Pictures logo. This is a reference to Producer Joel Silver, who produced this show. Ironically, the design is spot on, but the coloring of it is gold, not silver.
The trivia items below may give away important plot points.
After the end of season two, television critic Alan Sepinwall asked Rob Thomas which elements revealed in the finale were planned ahead, and Thomas replied, "We knew that Beaver was the killer of season two when we introduced him in season one. We knew his motivation, so playing him as the picked-upon, less-manly Casablancas boy was all by design." But Thomas also told Sepinwall that they did not plan for the eventual reveal that Cassidy had raped Veronica, until the writing for season one was all finished.
At the end of season one, episode twenty, "M.A.D.", after Veronica finds out Logan gave Tad G.H.B. the night of Shelly Pomroy's party, Veronica stands Logan up for their boating date. In one of the final frames, the flag of the yacht club can be seen and reads "Albacore Club". This presents a strong connection to the noir film classic Chinatown (1974), starring Jack Nicholson.