Do any mile collection programs allow you to claim retroactive points?

I flew at the beginning of March from Toronto to Tokyo with a 3 week stopover in San Francisco on a United ticket. Are there any programs that I can sign up to now that will let me claim the points from this past flight?

I'm new to this mileage thing... ...actually just found out that you don't always need to fly on the same airline to collect points. Normally I live in Toronto, but I'll be in Japan for at least a year. I'm hoping to tour around south-east Asia so any insight you have on cheaply flying around the region from the Tokyo area would also be appreciated.

Looking forward to browsing this site!