This seems to be an issue with expanded GRAM not being activated. Make sure to update your Sprint's firmware to the latest version. Please come back if that does not fix it.
Viewing post in Dreadline for Intellivision (digital version) comments
Problem has now been resolved. I was only downloading the update from Atari.com. Someone at AtariAge informed me that I needed to get the newer updates from AtariAge. Once I did that the game now works perfect. Also, thank you for such a cool game. I love the graveyard background with fog and the awesome picture reveal at the end. You've made a very fun game. This will be great for my Halloween show I do on my Youtube channel.
The latest 1.2 should be enough to work.
The main issue is that the emulator inside the Sprint was not reading the JSON properly, in particular the line that says "jzintv_extra".
That is vital for enabling expanded GRAM for Dreadline, otherwise graphics will be messed up.
Mechatron does not incur the same issue, but certainly having the latest firmware can't hurt.