The Book vs the Film!
Differences I picked up between book and film
FILM: Percy’s half-brother just walks into camp; Grover is captured by Luke and is sent looking for the fleece, in the book Kronos doesn`t almost raise but in the film he does
BOOK: You’re introduced to Tyson at the school that Percy goes to; at the end of the lightning thief Grover goes looking for the fleece and last in the book there is no mention of Luke trying to raise Kronos at this point.
Film vs Book
I think the descriptions are very effective but some of these descriptions are missed out completely.
Tyson’s eye: one large calf brown eye in the middle of his fore head.
The hippocampus: horses with silver fish bodies.
The Party Ponies: black Arabian bodies lower half of a stallion. Some with bows, some with baseball bats and some with paintball guns.
One of the differences between the book and the film is the part where there is a description of the sea Sirens. In the book they are described as vultures the size of people with grey talons and wrinkled pink necks. This part of the book was completely missed in the film.
A difference that is in the book and the film is the outfit that Polyphemus is wearing in the film it looks like an old t-shirt and a Scottish kilt but in the book it`s described as a baby blue tuxedo.