1, like Joram I missed out on getting the crystal skull on my first playthrough.
2, did'nt do much mindreading so I missed out on my free level & skill points from the avatar of sentinal island.
3, missed the easter bunny
4, kept dying in the lava room where you have to jump down onto the moving platform (when you go after Barnabus)
5, completely missed the fact that the Aleroth Harbour had an indoor section lol (don't ask me how because I just don't know lol).