How could they have known they were 10,000 years before Christ if Christ hadn't been born yet?
Yes you're right - this completely arbitrary date approx. 2000yrs ago as an origin is crazy.
Perhaps we should opt for a new standard were the year 0 is the year the Earth first formed. No more messy negatives - apart from for astronomers who, lets face it should be able to handle that kind of mathematics.
So we'd currently be in year: 4540000000 (based on the assumption that the earth is 4.54billion yrs old http://en.wikipedia.org/wiki/Earth_Age) and the movie in question could be entitled: "4539987992" <--- catchy huh?