If you use kamikaze on a map with map borders and start right into the map border, your hog goes right through it.

Kamikaze is also able to go thorugh indestructible terrain. No, I don't mean the indestructible terrain you can flip on and off with the game modifier from the game scheme.
I mean indestructible terrain which is forced by the map mask (red color in mask.png). You could easily test this with the Portal map.
The kamikaze hog goes through it without destroying the terrain.

Proposed solution: Make kamikaze hog explode when it hits the map border or (mask-type) indestructible terrain.

This affects 0.9.21 as well as post-beta versions.