The demo does not run OK (every games screen is corrupted) on the NES MiSTer core, and according to the core developer(s) the fault is on the game side, see here: https://github.com/MiSTer-devel/NES_MiSTer/issues/455, quite sure the game developer will understand what's going on quickly after the comment provided there.
Viewing post in TONY-Montezuma's Gold (NES) comments
The graphics and game play corruption is now gone, I was about to complain about the missing music until I read the changelog. But, the real complaint is - I get the impression that the traps got faster, I am just unable to pass the first droping door (or what it should be called). And this is from a person that completed both the Atari 8bit and Commodore versions several times. I tried both PAL and NTSC, all the same.