In the PAL version, there's an interesting glitch. When prompted to select a language before the title screen, you can press Triangle to cancel it, leaving you with nothing but blank spaces and hyphens where words would normally be. The glitch gets really interesting in Adventure Mode, because most bosses strangely swap their heads and dialogues with each others. You can get such atrocities as Papu Papu with Pinstripe's head, Komodo Joe with Oxide's and Oxide with Papu Papu's (Ripper Roo, on the other hand, remains untouched). Another difference is that Aku Aku/Uka Uka will be silent.
The game seems to change to the Japanese language when you do this (the only problem is that neither the voice lines nor the Japanese font are there, and that's why it doesn't work). The reason it seems to do this is because the CTR challenges in adventure mode will say "CBR" along with some missing characters. CBR stands for Crash Bandicoot Racing, which is the name of the game in Japan. As you've probably guessed, these challenges use the letters CBR instead of CTR in that version. This further supports the theory that the Japanese version was built off of the PAL one, also evidenced by the fact that it retains all the improvements from it.