The original lyrics to the movie's song "Toxic Love", performed by Tim Curry, had obvious sexual themes/implications, and various verses from the original song were cut and/or rewritten to make the song more appropriate for a children's movie. The original lyrics can still be found but the song's full version was never used.
Originally supposed to be released in November 1991 but the release was delayed to avoid the competition with Disney's Beauty and the Beast (1991). Instead, it was released in April 1992 and competed with Rock-A-Doodle (1991).
Tim Curry (Hexxus) and Robin Williams (Batty Koda) have both worked with director Chris Columbus. Curry; Home Alone 2: Lost in New York (1992). Williams; Mrs Doubtfire (1993), Nine Months (1995) and Bicentennial Man (1999).
When Zak carves Crysta's name into a tree he only gets as far as 'Crys' before she stops him and explains the pain he is causing for the tree. Although misspelled, stressing the word 'cry' is certainly a reflection of the tree's pain.