There was no follow-up raid because aerial photography showed that the new anti-air raid defences on the dam installed after the attack would have made a second raid suicidal.
Footage used to show the bombs as they skipped on the surface of the water towards the dams was drawn from footage of the bombs being tested. Backspinning the bombs gave them gyroscopic stability when skipping across the water, then held them against the dams as they sank. To conceal the backspin, which was still a state secret at the time of filming, the bombs in the footage were painted over frame by frame.
The squadron's mascot, "Nigger", was given beers to drink as depicted in the movie. However, the dog had a habit of urinating on people's legs which made the dog unpopular with many of the squadron's personnel. Also, the dog was killed when hit by a car, but unlike in the movie, the driver did attempt to avoid the dog and the occupants of the car were injured as a result. Any reports of Nigger's grave being opened, and the bones revealed proving not to be of a dog, are false. The grave was never opened, and is protected to this day.
Upon hearing of the immense 40% fatality rate sustained - with 53 men killed, along with 3 captured - Barnes Wallis is said to have burst into tears. Despite his expertise as one of Britain's leading wartime engineers, he was a pacifist at heart. In 1969, Wallis spoke of how "the most regrettable matter of the whole project was the fact that a large number of women and children drowned" in the 336 million tonnes of water that broke from the dams. It demonstrated how heavily the Dams raid weighed on his mind.
According to Richard Todd's autobiography, the scene that upset him most during filming was the finale where his character Guy Gibson goes off to write letters to the families of the men killed on the raid. Todd, a paratrooper combat veteran of World War II, had written such letters for real. The scene brought it all back for him.