To everyone who said Light Yagami just needed to write goku's name... Well, he already died a lot of times, and he sure could just come back and kick Yagami's butt... and search for his soul, and... well, kick his butt again...
And about Superman... He's been to almost every known paralel universe, he's the strongest being in universe(If you read some of his comics, you'd know he doesn't use all of his power, fearing he could kill his enemy or anyone close), and, seriously, he's TOO SMART!! I even saw him make a lobotomy in a guy who had mental powers using the laser eye combined with X-ray directly in the middle of the eye.
About the planet stuff... He already traveled millions of worlds, to find the cure for cancer, altough he didn't found it...
And why would Goku's head explode? O.o