-- What are some of the influences you see in this sequence from other cinemas (such as German expressionism) or other art forms? For example, consider this scene in relation to the work of Fritz Lang (who also worked at UFA).
The compositions and lighting are somewhat reminiscent of Lang. The sense of an inescapable doom that leaves your actions meaningless is also there in a lot of Lang's work (but also a lot of other places of course)
The titling of the sequence as Nighthawking obviously brings to mind Hopper, biographies of Hopper have stated that the picture nighthawks was inspired by the original Hemingway short story The Killers is based on and it seems like Siodmak worked with this in the film adaption. It being an adaption the hard boiled short story is obviously also an influence here, and the dialogue style comes in large part from Hemingway's original.
-- How does this sequence shift its visual design from realism to formalism, as it moves from the diner to the Swede's room?
The rush to the swede's room, vaulting the series of white fences that stand out in the blackness and then the turn of a corner up to the window and the room serve to seperate the two locations and add a dream like quality to the journey between them. The movie hinges on just why Lancaster's character is so accepting of his end, what is the one bad thing he did that he feels made his death inevitable, in the swedes room we are confronted with choices and actions that seem totally counter to normal human experience so it makes sense that we encounter them in a context that doesn't feel entirely real. The shift from realism allows things like the man and his shadow forming an audience for Lancaster and sets up the idea that we will venture into the past to 'solve' the unreality of lancaster's fatalism.
-- In what ways can this sequence from The Killers be considered an important contribution to the film noir style?
The idea of one bad thing leading to inevitable death however far you run or try to hide. The idea of an untouchable evil intruding into everyday working life. The chaotic shadowed dream state alongside the rational structured world.