The bug

Tripwire hooks have faces on the inside, even though these faces can never be seen without clipping inside of the block, making them completely redundant and possibly contributing to render lag. These faces do not exist in Java Edition.

How to reproduce

1. Place a tripwire hook on a wall
2. Enter Spectator mode
3. Fly inside

Expected results

There would be no inner faces.

Actual results

There are.

Further notes

The interior faces of the metal ring can technically be seen from the outside. However, it'd probably be better to say that the tripwire hook model is at fault here, since there's four faces defined for the ring in Java Edition that if present would occlude these interior faces.