Factual error: The system devised to get the height right was, in the film, said to have been thought of by the 617 Sqn crews following a visit to the theater. In reality it was devised by the 'boffins' at Farnborough.
Factual error: The Castle above the Eder-Dam is shown on the southern-side of the lake. In reality, this castle is on the northern side.