The plot point in question is the part of The Dambusters where Allied bombers bounced bombs across the surface of the Ruhr River to explode against the base of a huge Nazi dam. The pilots had to get their launch just right or the bomb would not blow the dam's structure at the right point, causing the entire damn to collapse.
In Guns of Navarone, Peck's squad of commandos race to destroy the Navarone super guns before the British transports get within their range. This mirrors the fleet's race to destroy the Death Star before it can fire on Yavin IV – although it wasn't positioned that way in Lucas' first edit.
The Mos Eisley spaceport sequence 45 minutes into Star Wars basically a giant riff on Casablanca.
Most of Casablance takes place in Rick’s Café – the original, unproduced play the movie was based on is even titled, “Everyone Comes to Rick's.”
In Star Wars, Lucas created Chalmun's Cantina.
You know the drill, shady under-the-table deals are made in dark corners, Figran D'an's swing orchestra providing ambiance, and alien barflies smoking pipes and hookahs.