Missing Bosses in Demo Mode

From Glitches

From the game Blaster Master for the NES.

If you watch the game's demo, it will eventually show two different demos of Jason fighting two of the game's bosses. If you play through the game and defeat those bosses, then end the game and watch the demo again, those bosses will not appear in those scenes. Jason will be shooting at nothing.

Taken with permission from Flying Omelette.