Willis H. O'Brien and Pete Peterson completed a significant amount of the stop-motion animation on a table in Peterson's garage.
The audio commentary by Phil Tippett and Dennis Muren on the film's DVD and Blu-ray release generated some ire among enthusiasts of Willis H. O'Brien. Many found the comments by Tippett and Muren to be condescending and misinformed as the pair lambasted the film and didn't offer much information with many of their statements ending with "I don't know".
To save money on an already tiny budget,the attacks on London and the ferry were filmed without sound. Many people are seen talking but there is no dialog. Sound effects were added later. The reporter at the ministry is shown in close up, but his mouth movements and dialog don't match. He also has a distinct American accent.