Sorry to resurrect this thread, but I didn't feel like creating a new one. My console run of Contra just got put up at SDA, and I watched it for the first time in a couple weeks, and it reminded me of some things. There are some fairly easily implemented improvements to this run that will shave off a few seconds. All of them come in Waterfall.
There is a glitch that I presume has to do with the way the screen scrolls vertically, where Bill or Lance (I love those names) can jump "higher" than they can normally, meaning they can reach ledges that they shouldn't be able to reach with their normal jumping height. Since the programmers inexplicably made it so that Bill and Lance always jump the same height and move at the same speed, that means that you will have to make two less jumps, which translates to less time. The guy who made this movie actually did it once, but later in the level. Here's the locations (that I know of):
There might be more places to do it than that, but those are the two that I accidentally did on a console numerous times. Sorry if this was already posted somewhere; I did a search and there wasn't much in the way of relevant Contra discussion. Anyway, I don't know if this is already known, but if someone wanted to improve this, this would be something to consider.