The original title means “April and the Rigged World”. As the non-literal English distribution title suggests, the steampunk is very light here. Obviously the abducted scientists are not doing any science under realistic premises à la The Difference Engine (1990), just fantasy action-adventure engineering. Weaknesses of the writing include:
Massive single-car, single-track elevated “trains” on cogs without adequate seating. Slower than the real steam-powered trains that existed 40 years before the turn into alternate history, and highly explosive for no reason. Surely a magnet for dirigible bombers.
Decades of war over all fertile land without popular uprisings. Who exterminated the Marxists and anarchists? Normandy does look cool though.
The plan to colonize other worlds with immortal plant life, which supposedly drives the entire plot, represents neither conservation nor any other desirable outcome unless the “serum” can be removed, of which there is no hint.
Hiding in the statue’s head is a bad idea. So many stairs! No other way out! Everyone can see the lights!
Avril’s total ignorance of the oak her grandfather loves. He would have taken her there as a child.
If the serum works on cats, rats, dragons and thousands(?) of plant species, why not people? Only because that would take the story out of matinee adventure territory and into science fiction.
The talking animals are stereotypes—except perhaps Chimène—as is the protagonist’s sense of betrayal by Julius and eventual romantic awakening with the same man.
The level of self-consistency in the writing is so poor that I have to assume it’s intentional: schlock across the board. Only the animation and humour sustain my interest.