These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Fire Shark
Anticlimax Boss: Many of the bosses can become this if you have a level 4 laser or flamethrower weapon. They WILL die VERY quickly.
In the arcade version, almost all the regular Mooks become like this.
Game Breaker: The Flamethrower weapon. At max level, it shoots out 6 streams of fire that sweep almost the whole screen except for directly behind the player character. Not to mention is does massive damage too...