D.B. Cooper Goofs [Possible Spoilers]

A few things don't add up about the D.B. Cooper story in Prison Break and what actually happened...
For example:
-Westmoreland presents Michael with a $100 bill from the skyjacking as proof that he is D.B. Cooper. However the actual ransom was paid in $20 bills.
-Westmoreland and others refer to the ransom as being $1m, and Westmoreland later reveals that the real figure was $5m, and that it had merely been lowballed to the press. Lowballed or not, the real reported figure was $200,000.
-The D.B. Cooper skyjacking happened in 1971. But T-Bag mentions that Westmoreland's $100 bill supposedly from the hijacking was minted in 1972...

So are these intentional? I mean surely the writers would have researched the facts if they were going to include it as a factor of their story!

At first I thought maybe Westmoreland was lying, just to get in on the escape, but I can't see any reason for him to continue lying, and even lie further, on his deathbed, so I doubt that could be it.

I suppose maybe they upped the amount from $200,000 because it isn't that much money today (not that i wouldn't want it!!) but the prisoners are far more likely to be falling over each other and themselves to get to $1m/$5m!
And so maybe then they changed the size of the bill from $20 to $100, after all its the same ratio between the $200,000 and the $1m Westmoreland originally claimed!
The 1972 thing is still a headscratcher though...