Dawson Casting: Pazu and Sheeta (both at approximately 13-14; it's never stated in the movie) are voiced in the Disney English version by (fittingly enough) James Van Der Beek (21) and Anna Paquin (17), and sound considerably more mature than their intended ages. Longtime fans of the original Japanese version have stated this as a point of contention, while others don't find it so distracting.
Ironically enough, in the Japanese version, Mayumi Tanaka and Keiko Yokoyama, both who were in their thirties (as were Barbara Goodson and Lara Cody from the dub from the 80s Streamline release, at 38 and 30, respectively), portray Pazu and Sheeta as high-pitched-sounding kids. It remains debatable over whose performance of these two characters are preferable.
Genius Bonus: The 1964 black comedy film Dr. Strangelove also contained a ragtag bunch of misfits in a plane trying to reach Laputa (in Russia) which was also the location of a Doomsday device, a comically-over-the-top choleric general, and a mad scientist with dark glasses who was hiding his allegience to a defunct evil empire behind an assumed name.
No Export for You: Ironically, the soundtrack of the US score is only available for purchase in Japan. The English dub with said soundtrack is admittedly included as a bonus feature on the Japanese Blu-ray, but it's still a bit odd. (The rescore is also on the Australian and UK BD releases.)