The game originally had a darker, more serious tone, akin to "Road Warrior meets Firefly." After the art style was changed to its final cel-shaded "rockabilly" look, the game story was changed and the dialog re-recorded to better fit it. This also freed the design team to create more zany characters, maps and missions that fit with the new style. These changes all were made during the last 10 months of development.
To meet the release deadline, near the end of development a portion of the game maps and vehicles were cut from the initial game launch. Most of that content was used in the expansion pack "The Secret Armory of General Knoxx," though some of it ended up in Borderlands 2.
The gun that belonged to T.K. Baha's wife, the Lady Finger, has an inscription on it that says "Omnia Vincit Amor" which is Latin for "Love Conquers All."
Many of the character's names have significance. Roland, Mordecai, and Lilith are from the Old Testament. Tannis is the city where the Ark is supposedly buried. Helena, Pierce, and Patricia are all variations on the middle names of one of the writer's siblings.
Sometime during the game's development, the art department at Gearbox wanted to completely redo the game's art style, from a realistic tone, to the more artistic, shaded art style seen in the final release. President of Gearbox Randy Pitchford was initially hesitant, as the game was no longer in the early stages of development, but agreed to the changes after the studio's art department protested.