1. The Score when getting a continue does not increase by 1 instead jumps straight to 9. Hard to tell how many continues you have used.
2. The amount of coins overflows when reaching 5 digits. So you go from 9999 to 0. Makes it next to impossible to unlock the two 9999 coin items in the shop. Didn't realize it was METALS and not COINS that were the currency for the shop. 
3. Can't back out of the character selection screen. Have to play and then exit via the pause menu.