It's actually 21 cards with the checklist being numbered 21. Here's a scan of the back of the checklist:
I'll add it to my backlog of checklists to be added if nobody beats me to it.
Trivia: The first 20 player cards are standard size, while the checklist card is double width. I haven't seen the original packaging, but would have to assume this means there's two stacks of 10 each on top of the checklist card.
ETA: If someone else creates this checklist, all card #s have a 'CR' prefix not noted on the checklist card.