Dr. Matt Pearce: You can give blood 20 times a year.
The American Red Cross allows people to give blood every 56 days, or approximately seven times a year, not 20.
Ben: I have a brother somewhere, but I've never seen him.
Throughout the rest of the series, it is established that Ben and his brother Jason grew up in an orphanage together. The episode "The Return" is centered around Ben returning to see the man who gave refuge to Ben and Jason when they ran away from the orphanage.
Ben: One transfusion from me, and viola! Two thousand year old man, meet the 2,000-year-old woman.
"The 2,000 Year Old Man" is Mel Brooks' and Carl Reiner's classic comedy skit, first performed in 1960. The spoken word comedy album was nominated for a Grammy.