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.
Not to mention "Heroes" by David Bowie as the "tunnel song".
Manic Pixie Dream Girl: Arguably Sam. Her mania manifests as a preference for unsafe seating arrangements in trucks and the music of The Smiths. Also she used to bang a lot of guys. Sam is a little less over-the-top than most uses of this trope, possibly in an attempt to ground the fiction in reality. She helps Charlie get over his issues and learn to live life to the fullest. Also literally has a pixie haircut.
However, Charlie's perception and treatment of Sam may show he sees her as a MPDG. From a narrative perspective and based on her scene near the end when she tells him to make himself happy, she could be seen as a aversion or a subversion of this trope.
Nightmare Fuel: Charlie's phone call to his sister is one for anyone who's ever had a sibling, friend, or relative with emotional issues
After Brad's goons beat up Patrick and Charlie intervenes, Brad quietly approaches Charlie in the principal's office and softly thanks him for doing what he did before leaving, revealing how torn up he is. While it doesn't excuse his actions, it still stings to know how bad he feels.
Patrick's breakdown in Charlie's arms, right after the aforementioned fight.
Charlie's anguished call to Candace, where he flatly asks if he's responsible for his aunt's passing.