When I visited as a tourist, why do ATMs only disperse $50 bills upon withdrawing large sums (i.e. $500) when Australia clearly has a $100 bill? Why does it exist when barely anyone uses it for regular transactions?
There's another anachronism from that movie around 34 minutes in (during the scene where the nurses are on a transport ship heading for the hospital) as the movie is meant to be portraying 1941: you can literally see the USS Arizona memorial in the background as pictured and circled below:

It's a nitpicky detail that made it on the final cut, since that wasn't built until 1962 (way after the war!).
That reminds me of a war movie I've watched, when Josh Hartnett's character said "I think WWII has just started" during the attack on Pearl Harbor. (That line is historically inaccurate).
In reality, people would just consider it the "war" (referring to the European theater) or "Jap invasion of America" marking the US entry into the conflict (the term WWII was not coined yet until after).
I think casino ATMs disperse them, but people's paycheck isn't handed out in cash (unless their payroll has issues) as a friend of mine got handed $3000 with just x30 $100 bills from his job as their system wasn't working at the time, usually they pay people via EFT.