I haven't played an awful lot, but it's fun so far!
I have one major bug to report, though: Whenever I press the down arrow when I'm charged for an attack, I get an error (Err:Link I believe) and it causes my calc to freeze and I have to pull a battery.

This is.....odd.
Which calculator?
Did you have an item selected? Which one? Was it a bottle? What was inside the bottle?

TI-84+SE OS 2.55MP (shush, I use it for the extra built in functions )
I tried it at various points in the game including with water selected. It also crashes when I go to use magic, then press down. And occasionally if I die and hit [2nd] too quickly, it glitches to an odd map area and when I move it causes it to crash.

Great game,  but has some bugs in the save/continue system. Maybe an update?

Would you mind describing it more? Which calculator model do you use?

Also,  does this game use the 6mhz or 15mhz mode?

If your calc supports 15mhz it uses that, else 6mhz

I am experiencing the same bug as Xeda112358. When I try to use an item in a battle, first the game freezes and the grayscale stops working (only black and white). After a few seconds, the screen clears and "error:link" appears. After that, I have to reset the ram for my calculator to behave properly (garbled screen, etc.). I even saw  a blue line of death once. I have a ti-84 plus with 2.55MP.

I found another minor bug: when there is options in dialogues, sometimes the bullet that indicates the selection doesn't move even if the other option is selected. It happens mainly in the first area.

P.S Reuben Quest: The Lost Mirror (ASM remake) works perfectly on my calculator (great game!).

Are you on the latest Reuben3 version?

Downloaded from ticalc.org 3 days ago.

Which item did you try to use?

I don't even have the chance to select one. It crashes as soon as I press "down" from the main battle engine screen (Left - Attack, Up - Magic, Right - Run, Down - Item). I tried while having 1 water and 2 water. I never see them from the battle engine, I know I have them because of the item menu ("mode" key).

Edit: I finally understood how it works and tested different items. Bombs work. Ginseng displays "50+ MP", but the game freezes. Everything else crashes the game.

Congrats @Sorunome!