While fighting about who was supposed to watch Kiara, Pumbaa calls Timon a 'fat fat fatty', which is exactly what Matthew Broderick (Simba) called Nathan Lane (Timon) in their fight in the Broadway play 'The Producers'.
Most of the original cast reprised their roles from the original, with the notable exceptions of Rowan Atkinson who was replaced by Edward Hibbert as the voice of Zazu the Hornbill in this film and its follow-up/predecessor The Lion King 1 1/2 (2004) and Jeremy Irons, who was replaced by Jim Cummings as the voice of Scar in this film, who also voiced him in The Lion King (1994) for the last few lyrics of the song "Be Prepared".
"Vitani" was originally "Shetani." It is possible to hear characters refer to her by that name. It means "Devil" in Kiswahili, however, and Disney may have thought it was inappropriate, thereby changing it to something a little less offensive. "Vitani" has no meaning in the Kiswahili language, from which most of the characters' names are drawn.
The trivia items below may give away important plot points.
Originally, when Nuka died, his last words were not "I'm sorry mother, I tried", but "I'm sorry mother, I tried. I guess I finally got your attention, didn't I?" This extended scene was not included in the final release.
Originally, when Zira dies in the end, she said "No, never" when Kiara offered her help, and let go of the rocks on purpose, thus killing herself. This extended scene was not included in the final release.