Great video & fun way to start off this topic (thanks for sharing @desiboyee !) I started out with Canadian banknotes & this 1979 $20 was my first & only offset printing error: Later, I wanted to get an error on a replacement note: I have one mismatched serial number on a Journey $10 but no scan to share. I then started to get into World currency & picked up this 2 digit mismatch RBS One Pound:
