Firstly, this is a fine choice for this year, and one I considered too (my piece is finished, but I'm going to send it to you on Sunday for (hopeful) publication on Monday, so mine becomes a three-part thing every Monday, if that makes sense).

One interesting point about the diner scene: Watch it very carefully and you'll notice you can't be sure both actors are in the same frame at any one point. The person opposite could be a body double. For the other brief moments in the film where both characters are together, the same is also possible (both in the wide shots and close ups of the final scene, for instance). A friend of mine had a theory at the time that putting both actors in the frame at the same time would produce an excess of quality that would cause the celluloid to melt, so Michael Mann had to be very careful how he shot it and only make it appear that they were in the same scene together. :)

Of course this theory has since been disproved in other films (most recently The Irishman). But perhaps their quality has diminished to safe levels. Also, I think The Irishman was shot digitally, so maybe that makes a difference.