Meredith makes the comment that you have to have a 6 antigen match to be a donor, this is wrong. In fact, a 6 antigen match is very rare. There have even been times where there was a 0 antigen match between the recipient and donor and everything worked out just fine.
When Arizona asks Alex to join her for the trivia night, Justin Chambers' tattoo is still visible on his right wrist. Normally, Justin's tattoos are always covered with make-up as Alex doesn't have tattoos. The watch on Alex hand switches from left to right during the shoots.