In retrospect, the Babysitter (Silverstone) is supposed to be like Helen of Troy. Men will risk thier families, jobs and freedom to sleep with her. Among the people who want Alicia are her ex (?) boyfriend and a manipulative wanna-be-a-gangster suburban rich boy, who drunkenly conspire a plan to spy on her. The manipulative rich kid dupes the ex into breaking and entering the house where Silverstone is babysitting then tries to rape her. Nuff said about the plot.
Two things make the plot unbelievable. First of all, Silverstone, taken as THE sole motive for a host of fantasies (some related and some utterly unrelated to the ending) and a rape attempt is not buyable. In reality, Silvertone is no Helen of Troy, but yet another link of good-looking hollywood sausage. More importantly, in the movie, her character is unexciting, bland and (ahem) clueless.
Secondly, the antagonist rich hood's rape attempt is paradoxical. He has sense enough to manipulate the Babysitter's boyfriend like an expert (a la Cruel Intentions), yet the during the last scene of the movie he smashes lamps on peoples heads and tries to rape Alicia in front of 2 small children. Any criminologist could tell you that most psychotics are usually not silver-tounged manipulators and vice versa.
On a final note, the writers could have used some of the time they spent on the fantasy sequences to develop the characters' backgrounds and motives. At least then the film might not have been such a pile of garbage.