- plopping a ball in hole 16 for an extra ball ("Ballyhole")
- scoring the short diagonals.
I'm sure there's more. I added dates to the flyer tour pages at:
https://bingo.cdyn.com/paper/
so you can use a couple browser windows and step thru the flyers chronologically to compare. Keep in mind that the design dates and mfg/release dates weren't always the same sequence, and I wouldn't be too confident when you're talking about a few months delta in the dates.