I'd like to give this game a shot, and as such have begun a bit of memory searching. An interesting thing is that a given earthling's data values are not stored in the same memory location each time, but rather it can change based on how many items are currently on screen. These values get used for a lot of things, such as the occasional funktronian who walks by in the scenery, as well as presents etc. If these things go too far off screen, then they disappear and thus the values then get freed for some other purpose. EG if earthlings go too far, it's common that they'll despawn and hide in some tree instead. Next, while messing around with a running present, you'll find a minor glitch to duplicate it.
http://dehacked.2y.net/microstorage.php/info/507217615/Toejam%20%26%20Earl%20in%20Panic%20on%20Funkotron.gmv
This works on all presents, but it's no use right now. It's an extremely inefficient method to get bonuses; but it's neat to see what effects it has. Apart from the slowdown it causes, you'll find that it caps the onscreen items limit, and thus prevents more stuff from spawning. This means it stops Toejam from being able to search nearby scenery, if doing so would spawn presents or earthlings. It also means that the poor rock disappears, since the sprite limit has been reached it seems. When doing it again a second time, you'll notice that as the Funk Scan initial confirms, there should be a girl hiding up in the tree. When you try to actually search it, you can definitely hear her, but you cannot see her nor does the funk scan detect her. Yet for some reason, you can still trap her.
Completely useless glitch, but still neat.