The fight between the Jabberwocky and the Black Knight was choreographed differently than what is shown in this movie. When Peter Salmon slipped and fell, writer and director Terry Gilliam decided it looked so natural that he edited the fight sequence to include the fall.
The monster costume was designed so that Peter Salmon had to wear it backwards, to make the Jabberwocky's leg movements more bird-like.
On the DVD commentary, Terry Gilliam said the budget was so small they could only afford one corridor. Many scenes were shot in a single take because he didn't have enough time or money for multiple takes.
Made on a modest budget of £500,000, this was filmed on the crumbling sets of Oliver! (1968) which were still in storage at Shepperton studios, ten years later. They had previously been re-used for the Albert Finney musical, Scrooge in1970. It also re-used costumes from Alfredo, O Grande (1969), according to Philip Kemp in Sight & Sound Magazine.
In some countries, this movie was promoted and released as "Monty Python's Jabberwocky", against the wishes of writer and director Terry Gilliam. After threats of legal action, the Python reference was removed from all subsequent re-issues.