I've been replaying every update as a party of a wizard, cleric, ranger and rogue and here's what I got so far. I'm on main branch 0.5.42 Public.
0. CRITICAL: NOBODY sells spellbooks and you can't get more! What's my wizard supposed to do now that he's at 100/100 pages used?!
1. You cannot scribe Grease into the spellbook as the spell isn't considered a wizard spell.
2. There's a scroll of mirror image present in the game but it's called hold person and has broken code for effect description. You cannot learn it and I am not sure if it does anything.
3. There's a scroll of hold person that teaches you blur instead.
4. There's a scroll of hold person that teaches you misty step instead.
5. Melf's Acid Arrow's acidified debuff goes away if the target takes any instance of damage while it's on.
6. Black Tentacles do nothing on the turn they're cast to enemies within their area of effect even though they technically enter the area for the first time on a turn.
7. The game has a hard time handling the pathfinding logic for characters with flight. It also really struggles with SHIFT clicking the tiles for things like levitate, misty step and shadow dodge.
8. Firebolt and Sparkle are missing their ray animations when they're used vs objects.
9. Flaming Sphere doesn't damage enemies who walk through it like its expanded description implies.
10. CRITICAL: Flaming Sphere damages ONLY ALLIES with its end of turn effect.
11. CRITICAL: The shine cantrip from Ring of the Lightbringers fails to cast itself - attempting to cast it will hardlock your game.
12. Cleric's Soothing Hand short description says it heals allies but it stabilises them instead.
13. If you have a Ranger with Goodberries or a Cleric with Create Food, the party won't prioritise their conjured items over food rations.
14. [SPOILER]If the Air Elementals during the Magister's Amulet fight are in the air, it's almost impossible to target them with a mouse cursor, you have to use their portraits to target them[/SPOILER]
15. Pathfinding struggles with understanding the additional jump distance granted by the jump spell.
16. There's a fair share of recipes that quite literally don't feature the items listed in the game (mostly the materials like slavestone).
17. Crafting recipes you've already learned can still be consumed, making you lose on some gold.
18. A few plot items seem to be missing the faction relic tag and thus cannot be given to anyone like [SPOILER] Mardracht's Journal [/SPOILER].
19. Party members automatically equip items they pick up sometimes, which can be really annoying with the "free caster hand" component rule.
20. A couple of crafting items don't get the magical tag when crafted, e.g. Doomblade Rapier.
I'll post more if I remember them.