The large oval in the center of the page depicts a scene from the movie "Flushed Away". Two rats are present; one stands on a large piece of equipment, while the other sits on the smaller one. Both rats are holding plungers and looking rather determined.
Considering the background of the scene is mainly blue and the equipment is mainly black, this would be a great opportunity to bring some color into the page. The rats themselves can easily be colored in with orange and brown, while giving the details on their bodies some nice shades of grey. The plungers can be colored a bright yellow for some contrast against the blue and black. For a more whimsical shape, choose a light green for the equipment the rats stand on. Finally, the background can be filled with a bright pink for a funky, pop art look.