Destroy Barney III
In the battle against the Barney clone, the guns on the clone's machine each fire a single barrage of bullets and stars, and then attempt to #send fight to restart their loop. They will also attempt to #send fight whenever they are shot. The problem with this is that there is another #send fight command where the :fight label should be. Because of this, after firing a single barrage, the guns will then become inert, allowing you to destroy them with no resistance.
When the Barney clone exits his machine to fight you, there is no idle command between his life meter display and the label jump afterward, so the life meter displays in a text window (pausing gameplay until it's closed) instead of the bottom-row message line whenever you shoot him. Once he is defeated, he attempts to #send DoorWindow:seethis, except there is no object named @DoorWindow on the board. The only object to fit this description is inexplicably bound to a stat that contains no code (not even a name). Because of this, to exit the board without the "zap" cheat, the player must run south after the clone leaves his machine so that he overwrites the solid tile south of himself with a lion, making a hole for the player to go through when he's defeated.
Inside Mechagodzilla, you are supposed to solve a Town of ZZT-style combination lock, where you must push columns of sliders and boulders by amounts corresponding to the correct digits of the code, and then press a button to verify correct input (forcing a reload if it's incorrect) and unlock a one-way gate with a pusher. However, there is nothing in the locking mechanism to impede the pusher's path if you don't push any of the columns, so you can simply press the verify button and unlock the gate immediately.