Quoted from WolfManCat:
I noticed if you shoot before the skill shot images are displayed on the DMD sometimes the score gets stuck overlayed on all the animations. Something similar happened during the shoot out mode, all four gunslingers were super imposed over the other animations. Also if the game sits idle for long periods the main music will hangup between modes. No choice to turn free-play off either, never understood why home roms have basic features nuetered.
I've never seen that Skill shot display bug - if you could provide instructions to recreate it I'd be happy to look into fixing it.
The bad guys in showdown are drawn in front of the score & other display animations on purpose. It's a design choice.
The music bug is a known thing. It doesn't have anything to do with being idle, though, that I'm aware of. I haven't managed to figure out how to prevent it, but it has gotten more rare in recent code due to attempts at fixing it.
And there's no choice to turn freeplay off because it's not meant for commercial use. There's literally no code to handle credits/pricing options, etc. Specifically because it's not super bullet proof.