In the original novel, the colors of the Life Clock change every seven years: yellow (birth-6), blue (7-13), red (14-20), red and black on Lastday, and black at 21. According to the audio commentary, the movie changed it to 30 because it wasn't realistic to have a cast with all of the characters under 21.
The waterfalls and steps Logan jumps into to get back into the dome are the "active pool" of the Water Gardens, in Fort Worth, Texas. At the time, the main pool was 9 feet (2.75 meters) deep. It was closed in 2004, after four people drowned near the spot where Logan and Jessica dove in. When it reopened in 2007, the main pool was 2 feet deep.
The "Love Shop" sequence originally ran about four minutes, but required re-editing for the movie to be granted a PG rating. A scene with Box making a nude ice sculpture of Logan and Jessica was also cut. A scene with several characters visiting the "Hallucimill" shop in Arcade was cut for its depiction of drug use. All of the additional footage and its background music were lost in what is now known as "the great MGM purge", when studio owner Kirk Kerkorian sold off what he could of the studio's extensive archives, and threw out the rest.
The "carousel" sequence is one of the most complex flying wire stunts ever done for a movie. A circular rig was constructed above the set, designed to rotate in sync with the revolving floor plate below. Initially, the performers were all supported by a single winch driving the mechanism for their thin support cables. The cables became tangled during rehearsal. Each stuntman had to be untangled and brought down from the rig in a maintenance lift. The rig was redesigned so each stuntman was on his own separate winch, with all of the winches connected to a "panic" switch that cut the power in an emergency. For reversal shots, the white crystal on the arena ceiling was built on the floor of the stage, and the performers were lowered down towards it. These shots were then filmed upside-down, to make it appear that the performers were moving upward.