Invisible enemies

[Mindcrime]

Is it normal for certain things to be invisible? Specifically, the missile-shooting enemies and the electrical damage area of the posts that come out of the ground have been invisible since I started the game. I've seen the missiles, but not the enemies that shoot them, and I've seen the posts that come out of the ground, but not the electrical arcs. However, once I defeated the level 2 boss and received the key to zone 3, I started seeing the missile-shooting enemies and the electrical arcs coming out of the posts. I checked my inventory and verified I didn't receive any other items when defeating that boss.

Just wondering if those things being invisible before defeating the boss, but visible after defeating the boss, is a glitch or intended design.

[Mindcrime]

Additionally, I noticed that the controls are now listed on the home/first screen. Before I defeated the level 2 boss, the words "MOVE", "FIRE", "ITEMS/MAP", "FIRE EXTRA", "SAVE", and "LOAD" were visible, but the keys/buttons were not displayed next to them. Now that I have defeated the level 2 boss, the keys/button are displayed next to those words.