Silent Hill: Downpour was originally planned to have a PC port. This version was likely cut due to delays with the console release. Evidence of the PC version was present in the game's early preview build, with some button prompts showing keyboard controls.
In an early trailer (which Konami never meant for release), a boss fight with the Monocle Man can be seen at the end. According to the trailers and some left over models, he was meant to attack with two large tentacles, both of which appear to grab the train cars from the Devil's Pit ride. The removal of his boss fight is speculated to be due to the early release deadline.
The truck of Travis Grady, the main character of Silent Hill: Origins, can be found in the streets of Silent Hill in Downpour.
If the player puts money in the jukebox at the Devil's Pitstop diner, it will play the original Silent Hill theme song heard in the opening FMV of the original game. This is also the song that DJ Ricks plays when he and Murphy meet.