An often happening is items not appearing in your trading list or clothing slots. Here are some examples:
A Jammer with the same name and user running in place, frozen speaking, while the real one is near by. Only a few Jammers are able to see it at once.
When midway apparent the void "sticks" to your character, black pets blend in well to the grey void color.
There are places that should appear blocked off, but you can go there anyway! One example is the staircase in the castle den: you shouldn't be able to sit on the wall!
What other glitches are out there (besides the Skyway Glitch)? Comment with ideas!