While looking through someone's playthrough, I noticed a few things that are way off and can actually hurt the game's realism. (Unlike my preference for the lights in the Mazerunner tunnel.)
1. The Marker switch diagram in the forechamber is not animated correctly. Not only does it not fit with the overall look of the imager, but it's actually a double image. (This doubling of the marker switch model was used to give a "focusing" effect to the image in the original RealMyst, as if the focusing mechanics of the forechamber imager were not perfect. I actually noticed this error myself.)
2. The rotating tower and its respective mountain are not only too small, but they're not in the right proportion compared to a location such as the planetarium or the library. (I noticed this error myself.)
3. The gear to turn the elevator in the Mechanical Age is less realistic with its motion. (And it has absolutely no momentum. I noticed this error myself.)
4. The gears in the top floor of the fortress have blank walls. (I know its something someone would rarely look at, especially with a flashlight, but I just wanted to point that out.)
5. The water in the fountain in Selenitic has a very (as said by the playthrough player) Jello-like consistency to it, and looks very odd.
6. There are several shader glitches as the mazerunner enters the final stop to the Myst Book. (I noticed this myself.)
7. The stalagmites and stalactites have a decidedly polygonal look to them in the mazerunner cave. (I noticed this myself.)
8. The videos in Achenar's Temple could be adjusted to fade in appropriately to remove all traces of the background from the original 1993 game.
9. Several painting textures in Stoneship and Mechanical are low-res. (This has been pointed out by some players.)
10. The Fortress Simulator hologram graphics in Achenar's room don't look so clear. (I'm not sure if that's an aesthetic decision, to highlight how the imaging system is somewhat primitive.)
...then it crapped the bed and stackdumped.
The Time-Traveling Stranger.