- Watching PJ's movies
(half the world should go to jail for that
)
More seriously:
- Mixing up Hurin and Huor
- Mixing up Huor and Tuor
- Mixing up Tuor and Turin
- Mixing up Celeborn, Celebrimbor, and Celegorm
- Not having yet read UT and most of HOME
- Skipping pages of CT's commentary in the two HOME books that I've read (Treason of Isengard and End of the 3rd Age)