During the reprise of "Absolutely Green", some of the cities have been covered in plants in different points (the World Trade Center is an example, which was covered in three different points).
When Llort locks Rosie in a dog transport box the hinge of the door of the box is on the left side, when Gus lets her out the hinge is on the right side.
In the full screen version, when Gus and Rosie leave Stanley to go home, some of their bodies start to vanish.
(at around 31 mins) When Gnorga and Llort are standing in front of the viewing mirror, Llort is drawn with only one leg.