Godzilla's roar was made by dragging a resin-coated leather glove up and down a contrabass and having the subsequent recording slowed down significantly.
Raymond Burr said that, contrary to popular belief, all his scenes were not done in one day, but over the course of six days. It was simply impossible to create all the sets in one day, especially the daylight scene filling in for Odo Island and the night scene on the hilltop during Godzilla's first rampage.
Al C. Ward, who later wrote the entire 171-episode run of Medical Center (1969), was given a choice of $2500 up front to write the American scenes for "Godzilla" or 5% of the profits. Ward, thinking the movie would bomb, second-guessed himself and took the money. He later admitted to telling students of his college movie writing classes that he always regretted the decision. It was estimated he could have raked in $5 million in his lifetime from residuals.
It is often said that the original Japanese version had an overt anti-American sentiment and contained references to the atomic bombing of Hiroshima and Nagasaki and to the firebombing of Tokyo, all of which were claimed to have been deleted in the American version of the film. Though debated, there is a passing reference to the bombing of Nagasaki in the original version and the implication that Godzilla is a by-product of American H-bomb tests is still present in the American version, although to a lesser degree.
All the scenes with Raymond Burr were added after the Japanese version of Godzilla (1954) was finished and shown to Japanese audiences about two years earlier.