To elaborate on the fireball issue: the spell is cast, the fireball goes flying, but the explosion simply doesn't trigger.
- Statues doesnt interact/dialogue menu doesnt show up.
- Door doesnt open after figurine is given to statue. (only encountered this once)
- You have to close and open the doors once before entering each corridor for the mummies to spawn inside.
In Anubis' temple, this is nearly 100% reproducible in the central room all the pathways branch from (the one that leads to the end chamber, and the 4 passages with levers).
This is also reproducible in the Monastery south of Vallaki. It happens in the last room of the second floor, as well as in the room containing Gilos on the third floor.