Fifteen Reasons Why and the Crimes of Crouch: Part 1

Grimmauld Place
This scene is added in the beginning for added effect:
 * Kingsley Shacklebolt sends him a gift, containing some golden snitch (Sent by Dumbledore, actually) where the words, I open at the close is carved. This is mentioned in the books, but it happens much later in it, whereas in the films, it first happens in the beginning.
 * The scene where Christopher looks at a Daily Prophet article on the disappearance of Alison Black is omitted.
 * The scene where Sirius Black talks to Alyssa White in private is omitted: a huge foreshadowing plot point that is seen in the books.

Arrival At Hogwarts

 * Alyssa White summons him while Christopher stares suspiciously at a window. In the books, he intends to talk to someone else.
 * In the books, Alyssa White is the only person at the table she summons Christopher to. But in the flims, her friends are there.
 * A scene is added where several Hufflepuffs caught on, and attempt to spread a rumor, but not before Professor McGonagall catches them and hands out detention, along with the deduction of 50 points each.

The Return of Alison Black

 * Alison Black arrived with Sirius Black instead of Lilly Black.
 * Sirius Black speaks with Christopher in private about his discovery, which took place in the Discover Eastpoint Room. This scene was never mentioned in the books.
 * Lilly Black arrives late in the scene where the entire Black Family eats at the Cafe (Mainely Wraps was once there). Whereas in the books, it is Sirius that arrives late.

Incident in Orlando

 * A scene is added where Christopher experiences a vision of his crush, already dating someone else, unintentionally obtaining the truth (due to his lack of Occlumency), which happens while he is flying just above Long Island. Unlike in the books, he actually knows how long they have been dating, which was around a year at the time (something that is mentioned later).
 * The scene where Christopher overhears a conversation about his crush's boyfriend is omitted.
 * The Ministry sends an owl to Christopher explaining his secondary crush is already dating, instead of a student telling him directly.

Peer Pressure

 * The scene where during evacuation, he is peer pressured by Malfoy and his gang is pushed slightly before the incident in Orlando. This is a canonical error because the day before, he was at a meeting, but Malfoy is already in class and his gang is probably elsewhere, but he was pressured in the Viaduct Entrance instead of at the Boathouse.
 * In the films, in addition to Jason Malfoy's gang during the peer pressure scene, several other Hufflepuff students join in on Malfoy's side.
 * A scene is added where Neville Longbottom (Herbology Professor) caught Malfoy and his gang of Slytherins and Hufflepuffs pressuring Christopher over his crush, and punishes them with detention and a referral to Professor McGonagall.
 * The consequence was later changed to a Friday detention after distributing false information about his crush.
 * The evacuation scene is omitted

The Battle of Hogsmeade

 * Alyssa White is omitted from the majority of the battle, because she was tortured and injured during interrogation, which took place prior to the battle versus in the books, she was tortured shortly before the battle's end. However, she does reappear moments before the end of the battle to witness the Dark Lord's demise either way.
 * Because of the omissions, Christopher Lewis took her part during the Wooden Bridge scene. Also, her friends that were standing at the other end of the bridge were omitted and were replaced with his past crushes including (by director request) Alyssa White's sister.

Preparations for the Battle

 * Alison Black, despite the breakup, is the one that brings down the Wooden Bridge, whereas in the books, it is Katherine Green that does it.

The Final Duel

 * In the films, Christopher and Voldemort duel in the Great Hall instead of the Viaduct
 * Because of this relocations, the students are watching the duel.
 * A scene is added where students like Alyssa White, and her "comrades" appear behind the door to the Trophy Room in the Great Hall.
 * The scene where Alyssa White mutters words during the final battle is added. Something that never is seen in the books.

Behind the Scenes

 * During the Covered Bridge fight scene, when Christopher is sprinting down the bridge, the actor underwent strict and serious training on sprints in rugged terrain such as this scene.