These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Aside from being involved in assassination, terrorism and violently attacking the heroine, Rippner qualifies simply because he was willing to go through with the assassination of Keefe even though it included Keefe's wifeandchildren.
Ending Fatigue: Several viewers didn't like the third part of the film because it mimicked the typical Knife Nut villain often seen in Wes Craven films, while others did not like the ending at the hotel because they found it unnecessary and odd that it ended with Lisa returning to the hotel right after a threatening ordeal like nothing happened and without getting questioned by the police.
Fan Preferred Couple: Lisa and Rippner, in spite of all the attempted murder on both sides as well as the intense chemistry between Rachel McAdams and Cillian Murphy, especially during the lavatory scene.
Idiot Plot: Some people feel this way about the assassination plot.
Mind Game Ship: Rippner's and Lisa's "relationship" is practically built on this, what with the film revolving around the psychological mind play between them.
Moral Event Horizon: Rippner more than likely crossed it a long time ago as this seemingly is not the first time he has been a part of assassination and terrorism plots, and he mentions the Keefe assassination is his last job, but viewers are divided between which of his actions shown were worse—strangling Lisa in the lavatory, knowing that Keefe's family will get killed in the assassination and willingly allowing it to happen, or trying to kill Lisa in the end of the film.
Mondegreen: A common misinterpretation in the Fandom is Rippner's line in the lavatory. He says, "I never lied to you, Lis'." However, many mistakenly hear it as, "I never liked you, Lis'."
Narm: For those who found Rippner getting pissed over a seabreeze just a little humorous.
No Yay: Rippner and Lisa. Rippner is a Ax Crazy murderer out to kill Lisa's father and other people and Lisa herself. There's some sexual tension between the two and the scene in the airplane bathroom where he accosts her was dripping with rape metaphors. Word Of God also says that Rippner developed feelings for Lisa in the entire time he was watching her and that he was jealous of the man who gave Lisa her scar and raped her.
Padding: Not for the film itself, but for the end credits (which are artificially extended to make the film longer, which is why a movie that only runs 85 minutes has an end credit sequence that lasts for around nine).
Paranoia Fuel: Wes Craven played on the paranoia of flight: the isolation, claustrophobia, the feeling of being trapped, and sitting next to a complete stranger, not knowing who they are or what kind of person they are.
Signature Scene: The lavatory scene and when Lisa stabs Rippner in the neck with a pen.
Lisa running in heels. Though, it's justified, given there is a Psycho for Hire chasing after her.
Rippner unprofessionally following Lisa to her house, an unfamiliar environment where he would be at a disadvantage. Granted, he wasn't thinking straight due to being pissed because he just got stabbed in the windpipe with a pen, but one would think he would act more professionally and slip away into the shadows instead of letting his emotions get the better of him.