Awesome Music: Creedence Clearwater Revival's "Bad Moon Rising" makes a huge impression, somehow, despite the fact that not much really happens while it is playing. (The great transformation scene does not take place to this tune, but to Sam Cooke's version of "Blue Moon.") Also, Elmer Bernstein composed about eleven minutes of music for the film, which was so good that the technoband Meco based an entire album on it.
Idiot Plot: If David and Jack has just stayed on the road as they were told to do several times, instead of deciding to travel across the moors at night, they wouldn't have been attacked by the werewolf and the rest of the plot wouldn't have happened.
Narm: For some, the ironically upbeat songs picked for the soundtrack kinda ruin the moments they accompany. A YouTube commenter once remarked on a clip of the transformation scene they nearly left the page because they thought the clip, featuring David's horrific transformation accompanied by jazzy, romantic crooning, was a parody.
Jack is killed by the werewolf, and David doesn't find out until he wakes up in the hospital. When Jack visits David as a corpse, he mentions that there were a lot of people at his funeral, far more than he was ever expecting, and also that a girl who was in love with him had Sex for Solace with some jerk. It's only touched on briefly but Jack's family and community lost him.
At the end of his visit, Jack tells David that there really is such a thing as the supernatural and evil forces, and begs David to kill himself before more suffer his fate. David begins crying and Jack begins to falter, and begs him not to cry too.
During his second visit, Jack glances over at Alex's bedroom where she is sleeping. It's then that it hits you that he will never get to have sex, which his friend just enjoyed.
When the transformation scene comes, David is writhing in agony as his body forcibly converts into the werewolf. Right before it really starts, David apologizes to an absent Jack in tears and insists he didn't mean to call him a walking meat loaf, but Jack wouldn't be able to help him even if he was there.
During the nightmare scene, David dreams his family is slaughtered by Nazi zombies. It's pretty horrific on its own, but considering that David is Jewish and was probably born only a generation or two after the Holocaust, the zombies being Nazis makes the whole scene even sadder. The concept of watching your family's peaceful afternoon get destroyed and them getting brutally massacred is heartwrenching, too, especially the kids who were just watching The Muppet Show.
Having realized he must go through with Jack's warning, David calls his family. He gets an answer from his little sister, who begins bickering with him and informs him that their parents aren't around. David grows visibly upset, and tells his sister that he loves her, and to tell the same to their parents since he realizes he will never get to say goodbye to his parents.
The man in the subway confronts David posthumously at the theater and growls that thanks to David, his wife is now without a husband and his child is now fatherless.
The ending. After wreaking havoc (partially unintentionally) in the square, David has been herded to a dark alleyway. Alex goes to him, and tells her that she loves him. After a moment, David visibly softens... But lunges anyway, and is shot and killed, ending the film.