A number of character have dialogue that references previous roles. Robbie Williams' Dougal states he likes Florence as he "offers her protection" a line from his song "Angels".
The lines on either sides of Zeebad's head resemble a cartoon drawing of a Christmas tree without decorations, Zeebad's intentions include making the world a permanent winter, the season in which Christmas takes place.
When Dylan is supposed to be playing guitar for Ermintrude's concert, he nearly falls asleep before coming round and starting to play and sing 'You Really Got Me' by The Kinks however Dylan is playing an acoustic guitar whereas the music has clearly got an electric guitar and not an acoustic one playing, this is particularly noticeable during his solo at the start of the song.
After Train transports everyone across the narrow bridge over the lava, he slouches down to the ground in relief. In the next shot he is standing straight, looking normal.