I had heard the Coen brothers mention the influence of film noir detective movies on "The Big Lebowski" before. I had some idea of the typical elements of film noir when I heard them say this, most notably the wildly convoluted mishap-packed plots, but seeing "The Big Sleep", with Bogart and Bacall really made the parallels and influences apparent.
Whether any of these things were intentionally done or not, I don't know. But they stood out to me.
- The title. Big and Big.
- The rich gentleman in the wheelchair. Called "the General" in The Big Sleep and "Mr. Lebowski" in The Big Lebowski. They both speak in high philosophical terms, prone to oratory.
- The butlers belonging to these gentlemen.
- In the Big Sleep, one of the General's daughters, Carmen, behaves much like Bunny in the Big Lebowski. Throwing herself at Bogart. As when Bunny propositions The Dude.
- The use of the term 'shamus' to denote the private detective. This is in movies other than The Big Sleep too, but the scene in which it is used in both Bigs is very similar in other respects.
- The reading of the ransom note. Bogart reads the note to himself, mumbling while the note is shown on screen, same as the Dude does. Though Bogart is not "doing a j" while he reads.
- The ubiquitous presence of alcohol. Bogart, always drinking. The Dude, always drinking. How people got anything done in those days, I'll never know.
There are more, just getting started, but I'm out of time. Feel free to add more of your own.