In the original script, King Agamemnon was introduced as: "The warrior took off his helmet, revealing someone that looks exactly like Sean Connery, or an actor of equal but cheaper stature." To Terry Gilliam's surprise, the script ended up in Connery's hands. He expressed interest in the part and his agent approached them for the role.
Ruth Gordon was cast as Mrs. Ogre but was injured before production. Katherine Helmond was originally slated to play the role in heavy make-up to look like her husband, but then decided it would be funnier if Mrs. Ogre was an ordinary person. Terry Gilliam agreed.
According to Terry Gilliam, David Rappaport believed he was given his part for his acting ability alone, without size being a contributing factor, and as a result, did not socialize with his co-stars. During the Invisible Barrier scene when the other bandits retaliate against Randall, it was basically the actors expressing their frustrations with Rappaport.
Whilst filming the sequence in Sherwood Forest, in which the Time Bandits inadvertently crash into Vincent and Pansy's carriage, Terry Gilliam had scaffolding built for the actors to jump off. When directing the scene, Gilliam instructed that they were to jump in such a way as to land around Michael Palin and Shelley Duvall without actually falling on to them. To better illustrate what he meant, Gilliam then climbed to the top of the scaffolding and without hesitation jumped off, only to plummet directly on top of Shelley Duvall.
In 1996, Terry Gilliam and Charles McKeown collaborated on a script for Time Bandits 2, bringing back most of the original cast, with the exceptions of David Rappaport and Tiny Ross who had passed away a few years before, and owing to Jack Purvis being paralyzed from a car accident, his character was written to be in a similar state. But following the death of Purvis, the project was shelved indefinitely.
Young Craig Warnock, who played Kevin, won the role after a wide search for the right child actor. An agent had seen Warnock's brother and sent him to an audition. That Craig went with him was merely a coincidence. Director Terry Gilliam, however, took more interest in Craig than his sibling, noting that the young man seemed rather intelligent yet aloof and quiet, as opposed to the stereotypical "cute" little boy.
In the published screenplay, there are several black & white stills from scenes that do not appear in the final film. These include the 'spiderwomen' sequence and Agamemnon giving Kevin a knife (this is later used when Og takes it from Kevin's satchel to unlock their cage). Other deleted scenes included Kevin waking up at night to find his bedroom flooded with water and a pirate ship sailing through his window and the bandits trying to rob a bank in 22nd century London. Terry Gilliam stated at the 2011 Bradford Film Festival in the UK that he believes all the cut footage to be lost.
On the Special Edition DVD Terry Gilliam explains why Marcus Powell is still credited as Horseflesh, even though he is apparently never seen. As it turns out, Horseflesh can be seen standing next to David Warner's Evil as he gazes into the bowl of water to track the Time Bandits at one point in the film.
George Harrison was frustrated with Terry Gilliam's stubbornness, as evident by the lyrics to Harrison's song "Dream Away". Harrison even once told Gilliam he reminded him of John Lennon, because he was so difficult and "bolshie." It was the thing that Gilliam was most proud of that Harrison ever said to him.
In the screenplay, when the Supreme Being chases after Kevin and the gang, He initially appeared as a "classical" depiction of God: robes, white beard, etc. A picture of this version of the Supreme Being appears in a published book of the screenplay, suggesting the Supreme Being scenes were filmed as written, but ultimately the "classical" depiction was replaced with the "floating head" version of the Supreme Being seen in the film.
The Evil Genius's apparatus on his head was influenced by H.R. Giger's work on Alien (1979), which also starred Ian Holm. Coincidentally, one of the Evil Genius's lines is "And the day after tomorrow." Two decades later, Ian Holm would star in The Day After Tomorrow (2004).
The whole notion of casting a film with dwarfs came from Terry Gilliam's memories of growing up in the San Fernando valley where a circus used to roll into town each year and local kids would find odd-job work with them.
Terry Gilliam first came up with the idea in 1979. He had wanted to do an entire film from a kid's point of view. The only problem was he felt he needed to give the protagonist child a group of people of similar height to surround him, because a kid couldn't carry an entire movie. He combined those thoughts with the concept of committing crimes while time travelling, making it possible to get away with the thievery because it had not happened yet.
Terry Gilliam hadn't directed in years, and his first day back behind the camera took place on top of a mountain in Morocco in 130-degree heat. After struggling to get things right, Sean Connery helped by strongly suggesting to his director that he shoot his parts first and let him leave before working with Craig Warnock, who was living through his first day ever on a movie set. Connery also informed Gilliam they would deal with the star actually getting on the horse during post-production.
According to Terry Gilliam and Michael Palin's interview on the DVD, David Rappaport was so into the character of Randall that he didn't socialize with his co-stars and kept demanding close ups on himself.
Terry Gilliam described Sean Connery's career at this point as "at it's nadir". Fortunately, Connery was a Monty Python fan and signed on for a part of the gross. It also happened that Denis O'Brien was a former golfing partner of Connery.
Denis O'Brien wanted the soundtrack peppered with George Harrison songs and 'Heigh-Ho' type music reminiscent of Snow White and the Seven Dwarfs (1937). In the end, only "Dream Away" appeared in the credits. The song was to originally appear on the announced Time Bandits soundtrack album. However, when that failed to materialise and Harrison was finalising the tracks for his Gone Troppo album, he decided to include "Dream Away". Although the Gone Troppo album was a commercial failure, "Dream Away" became a popular tune.
Agamemnon's wife glares at him, and he sentences her three courtiers to execution. These are references to Greek mythology, in which Agamemnon and Clytemnestra hated each other and their marriage ended in murder.
Terry Gilliam came up with the idea for the ogre's ship to be a hat on top of a giant's head from a painting by Brian Froud. Moreover, a lot of tall men were initially considered to play the giant before wrestler Ian Muir was eventually cast in the role.
In his book Monty Python: The Case Against Irreverence, Scurrility, Profanity, Vilification, and Licentious Abuse, Robert Hewison describes the dwarfs as a comment on the Monty Python troupe. The nice one, Fidgit, is said to represent Michael Palin; the self-appointed leader, Randall, John Cleese; the acerbic one, Strutter, Eric Idle; the quiet one, Og, Graham Chapman; the noisy rebel, Wally, Terry Jones; and the nasty, filth-loving one, Vermin, Terry Gilliam.
On his first day of filming, Craig Warnock was reportedly so overwhelmed at meeting Sean Connery that their close ups had to be shot separately until the boy had adjusted to the veteran actor's presence, reportedly at Connery's own suggestion. In his part of the film's audio commentary, Warnock says he remembers Connery being "very friendly and down to Earth" and joked that the scene where he rode off into the dessert with Connery on horse back probably made more women jealous than kids.
The cowboys, Greek archers, tank, spaceship (Micronauts Mobile Exploration Lab), and all of the attackers that fight 'Evil' at the end are actually the counterparts of the same toys seen in Kevin's room; in some shots as Kevin runs through Evil's fortress, giant 'Lego' blocks can clearly seen as part of the fortress itself.
Denis O'Brien was against the ending of Kevin's parents blowing up and Terry Gilliam had to fight to keep it in the film. O'Brien was only convinced that the violent ending could stay after an advance screening of the movie was held for an audience full of children. The first child who was asked what his favourite moment of the film was excitedly proclaimed, "The parents being blown up!"
Agamemnon was originally supposed to appear at the climactic battle against Evil leading an army of Greek soldiers and being killed, but it could not be worked into Sean Connery's schedule (they only had him for about two weeks, as his role was basically a cameo). Having Connery appear as the fireman at the end was the compromise they devised to bring things full circle for Kevin. Agamemnon's death was given to Figid.