* AdaptationDisplacement: The novels' existence comes as a surprise to many. The film is actually a rather faithful adaptation of [[Literature/KPax Dr. Gene Brewer's 1990 novel]], which itself has three sequels.
* MarySuetopia: The description of prot's homeworld is basically a perfect anarchist, agnostic society with no violence, everyone is vegetarian, there are no schools, criminals are not punished; they are simply "reasoned" with (or they ''would'' be reasoned with if there were any there in the first place).
* JerkassWoobie: Some of the patients are generally unpleasant people, but they are suffering from mental disorders which may or may not be the reason they act that way. Sal is the best example, he's surly, rude, and tells people they stink. However, he used to be a normal man working as a doorman at a hotel for years, when suddenly one day he began to think people stank. In the book it's a bit played for laughs, in the film, Sal telling prot "I tried to tell them, but they put me here, and...this place smells ''worst'' of all" is TearJerker with the delivery of the line. He then tells prot that prot ''doesn't'' smell, which is why he's hoping prot can help him.
* TheWoobie: Good god, [[spoiler:Robert]]. [[spoiler:Father dies from a work injury at an early age, girlfriend gets pregnant and to support her you have to take a dead-end job in the same place your father worked (possibly even the same job, it isn't specified), and then one day you come home from work to find your wife and daughter raped and murdered in your home]]. Little wonder he was DrivenToSuicide.
** The book makes a good deal of the patients this. The reason Howie is obsessive compulsive is because his father was demanding and never tolerated mistakes, and Howie loved him so much he was determined to learn ''everything'' so he could please him. Ernie meanwhile had a father who would run emergency alarms in the middle of the night, shouting the family awake and out of the house. The book mentions that Ernie's current state is a big improvement from when they first got him, where he would jump every time someone sneezed.