Twilight: Look, I appreciate the offer but I'd really rather do this on my own. Applejack: No can do, sugarcube! We sure ain't letting any friend of ours go into that creepy place alone. We're sticking to you like caramel on a candy apple! Pinkie Pie:Especially if there's candy apples in there! (other ponies nod in agreement; pause; Twilight Sparkle glares at Pinkie Pie) Pinkie Pie: What? Those things are good.
Picking up from the last episode, Nightmare Moon departs as dramatically and suddenly as she arrived, leaving the citizens of Ponyville wondering what to do. Twilight Sparkle returns to her house to do some research, putting the baby Spike to bed beforehand. As she searches frantically for information, Applejack, Fluttershy, Pinkie Pie, Rarity and Rainbow Dash show up at her library in the hopes of getting some answers. She informs them of her studies on Nightmare Moon and the only thing that can possibly stop her: the Elements of Harmony. With the help of Pinkie Pie, Twilight finds a book on the Elements of Harmony which names the five known ones (Honesty, Kindness, Laughter, Generosity and Loyalty) and pinpoints their last known location... in an abandoned castle in the Everfree Forest.Twilight sets out for the ruins, and reluctantly allows her new acquaintances to tag along. This proves fortunate, as Nightmare Moon is following them and her attempts to thwart their quest give Twilight's companions a chance to show her their strength of character:
When a collapsing cliffside leaves Twilight in a Literal Cliffhanger situation, Applejack uses her honesty to reassure Twilight and convince her to let go... dropping her into the waiting hooves of Fluttershy and Rainbow Dash.
When a rampaging manticore attacks the group, the kind-hearted Fluttershy breaks up the ensuing fight and pacifies the manticore by removing a thorn stuck in its paw.
When the girls are threatened by terrifying illusions conjured up by Nightmare Moon, the happy-go-lucky Pinkie Pie teaches her friends to literally laugh in the face of danger with a catchy song and helps dispel the illusion.
When the path over a river is blocked by a foppish sea serpent lamenting half of his mustache getting cut off, Rarity sympathizes with his ruined look and cheers him up by generously offering a sizable chunk of her tail as a replacement.
When a broken rope bridge over a deep gorge bars the path, Rainbow Dash is tasked with flying to the other side and fixing the bridge. Nightmare Moon takes on the form of a trio of performing Pegasi and offers Dash fame and fortune on the condition that she leave her friends behind. Rainbow Dash is tempted... but chooses to remain loyal to her friends.
On finally reaching the keep, Twilight investigates the Elements of Harmony and tries to trigger the "spark" that is said to make the sixth Element appear. Just then Nightmare Moon appears and steals away with Twilight and the Elements in an effort to prevent this from happening. Much to her surprise, Twilight refuses to be cowed:
(Twilight Sparkle paws the ground, preparing a desperate charge) Nightmare Moon: You're kidding. You're kidding, right?
A brief struggle ensues as Twilight tries to recover the elements but eventually Nightmare Moon simply smashes them to bits. All hope is lost......then Twilight hears her friends coming to her rescue, has an epiphany, and the seemingly-destroyed elements activate. Twilight explains to a baffled Nightmare Moon, that the real power of the elements was within her five friends and herself realizing how much they meant to her was the "spark" needed to awaken the Sixth Element, Magic. With the combined powers of the Elements of Harmony, they make swift work of Nightmare Moon.As the sun finally rises, Princess Celestia reappears to congratulate Twilight and her friends. She was aware of the prophecy and knew Twilight had the power to save the world but only told her to make friends in the hopes that her student would learn the power of friendship and allow its power to spark the Elements. She proceeds to reconcile with Nightmare Moon who has returned to her original form... Princess Luna, Celestia's long-lost sister. Turns out that the two sisters in the original legend of Nightmare Moon were Luna and Celestia. Go figure!Celebrations are in order, Luna is ready to resume her duties of raising the moon at night and Twilight Sparkle is ready to return to Canterlot... except the once-antisocial unicorn is reluctant to leave her new friends so suddenly. With Celestia's blessing, Twilight decides to remain in Ponyville and continue her studies on the magic of friendship.
Aside Glance: While Rarity is talking about having just cut off her own tail, Pinkie Pie turns her eyes briefly in the direction of the camera.
Batman Gambit: The first of several from Princess Celestia. Knowing the truth of the prophecy of the return of Nightmare Moon (having banished her in the first place), that the Elements of Harmony were the only things that could defeat her, and that she needed a group of friends to wield them, she sent Twilight Sparkle to Ponyville. The Princess knew enough about her student that not only would she find a way to make friends as ordered, but would also not give up on her quest to prevent the reign of eternal night and succeed in finding the elements in time to defeat Nightmare Moon.
Be Careful What You Wish For: Twilight Sparkle didn't want to make new friends and found out later that "just when I learn how wonderful it is to have friends, I have to leave them." That is a milder case though as it turns out Celestia lets Twilight stay in Ponyville with her new friends anyway.
Beneath the Mask: Turns out that the evil Nightmare Moon was really just a lonely pony who missed her sister.
Big "NO!": Nightmare Moon lets one out before getting blasted with the Elements Of Harmony.
A Chat with Satan: Nightmare Moon does this to Rainbow Dash when she's off alone by attempting to tempt her into forsaking her friends for the chance to live her dream. Rainbow Dash is quick to refuse and help her friends.
Cry Cute: Twilight spent the episode treating her future friends aloof and uncaring. When they showed up to help her during the showdown with Nightmare Moon, she cries a tear of joy and finally warms up to them.
Despair Event Horizon: Twilight seems to come close to this when Nightmare Moon smashes the Elements Of Harmony, the only thing capable of defeating her, right in front of the poor girl. Thank goodness Twilight's friends showed up...
Dick Dastardly Stops to Cheat: Nightmare Moon would have gotten away with the Elements scot-free if she would have just stopped trying to trip up the Mane Six.
Easily Forgiven: A bit of magic and one "I'm sorry" are enough to reconcile Princess Luna. Not too surprising considering she was the one who spent all that time imprisoned which Celestia can't have wanted but was forced to do (indeed season four touched upon this, Celestia did all she can to reason with Luna but was ultimately forced to use force); Word of God states something was corrupting Luna and the corruption was finally driven out when (as mentioned in another episode and explored further in the comics) the heroines activate the full potential of the Elements.
Evil Gloating: Nightmare Moon does this to Twilight after smashing the Elements of Harmony right in front of her, telling her that she never had a chance of stopping her and has failed to save the world. Twilight's friends provide her with a very effective Kirk Summation.
Evil Is Hammy: Nightmare Moon chews more scenery than the rest of the cast put together.
Exact Words: In part 1, Celestia responded to Twilight's concerns by telling her "you simply must stop reading those dusty old books!" This was entirely true — the correct course of action was to go out and make friends. She never said she didn't believe Twilight.
Face Your Fears: The message of Pinkie Pie's song, 'Giggle at the Ghosties'.
Gambit Roulette: Princess Celestia knew what was going to happen with Nightmare Moon returning but the only action she took was to send Twilight Sparkle to get out more because she knew she would find a group of friends matching the Elements of Harmony and make it through Everfree Forest with them and then figure out how to work the Elements. As mentioned above, the bad guy does a wonderful job contributing to this outcome too. Word of God has stated that she was grooming Twilight specifically for the role, but even if she were wholly omniscient, it would still be a Roulette.
Hair Reboot: The Elements of Harmony completely fix Rarity's chopped mane.
Hidden Depths: The quest for the Elements Of Harmony reveals these in the group to Twilight Sparkle and the audience.
High Fantasy: Travel through a dangerous location to retrieve magical relics and defeat an ancient evil to save the world. The story is like freaking The Lord of the Rings in half an hour; with ponies.
Hope Spot: Twilight feints her way past Nightmare Moon and seemingly activates the Elements Of Harmony with her magic. Then Nightmare Moon crushes it and the Elements to bits.
Leave Your Quest Test: Nightmare Moon offers Rainbow Dash a chance to pursue her dreams by joining the "Shadow Bolts," but only if she abandons her friends. Rainbow Dash is tempted at first but quickly rejects the offer when this condition is forced on her.
Literal Cliffhanger: When the ground gives way beneath them, Twilight and Applejack are left hanging while the two Pegasi carry Pinkie and Rarity to safety.
Love Redeems: The Elements of Harmony purge the Nightmare out of Luna and then sisterly love finishes the job.
Mundane Solution: How did Pinkie Pie find a book on the Elements of Harmony? "It was under 'E'!"
Rampage from a Nail: Fluttershy realises that this is the case with a monster that's attacking them, and is able to calm it down. The first part of the trope was invoked by Nightmare Moon, who was the thorn in its paw.
Secret Test of Character: Double subverted. Nightmare Moon was not testing their character but her traps served as such for Twilight's purpose.
Space Whale Aesop: Dear Princess Celestia, no matter how strong and smart you may be, there are some things you just can't do alone. Friends have a special bond that has more meaning than you can find in any book. So cherish your friends, nurture your relationships with them and always hold them near and dear to your heart because together you can smite evil with an awesome rainbow Wave Motion Gun because friendship... is magic.
The Mayor sending her guards to attack Nightmare Moon, only for her to erupt and frighten them is reminiscent of the scene in Sleeping Beauty where Maleficent curses baby Aurora. Even the dialogue is word-for-word.
The parade and music in the coda are an obvious shout-out to "Augie's Great Municipal Band" at the end of Star Wars Episode I: The Phantom Menace.
Stab The Salad: Rarity yanks a scale from the sea-serpent's neck with her teeth and slashes with its sharp end, causing the serpent to collapse... at the horror of her cutting off her own tail.
Take My Hand: When the ground gives way under the ponies, Applejack grabs a branch while sliding down and manages to catch Twilight by the hoof. How they're able to hold onto each other without fingers isn't explained.
Talking Is a Free Action: As Twilight is delivering her speech about how the ponies all represent the Elements of Harmony, Nightmare Moon does nothing to stop all six from activating.
Tearful Smile: Twilight, upon realizing that these five quirky ponies, who insisted on helping her in her quest, are indeed her friends.
Pinkie Pie:When I was a little filly and the sun was going do-o-o-own... Twilight Sparkle: Tell me she's not... Pinkie Pie:The darkness and the shadows, they would always make me fro-o-o-own... Rarity: She is.
Traumatic Haircut: It was considered a big deal when the sea-serpent lost his part of his mustache; himself and Rarity thought so.
Twinkle Smile: Pinkie Pie during her song, although the twin sparkle is in her eyes, not teeth.
Unmoving Plaid: The end of Rainbow Dash's tail is ruffled from Applejack pulling it, but the stripes of colour on it don't.
Verbal Judo: Ironically involving nonverbal communication; Fluttershy calms the manticore by walking up to him and acting friendly.
Villainous Breakdown: Nightmare Moon's Smug Snake personality goes away really fast once the Elements of Harmony are activated. This is unsurprising since she spent a thousand years imprisoned in the moon the last time they were used on her.
Visual Pun: During Pinkie Pie's song, when she sings "The darkness and the shadows would always make me frown" and demonstrates this with her facial expression, she's looking down from the top of the screen, upside down, so she's in fact already "turning that frown upside down".
Wax On, Wax Off: Celestia's apparent dismissal of Twilight's fears of Nightmare Moon's return, and her demand that she make some friends instead, turns out to be a necessary step to defeating Nightmare Moon.
Win-Win Ending: The heroines save Equestria from Nightmare Moon's attempted eternal night. In the process, Nightmare Moon is reverted to her pre-villain identity as Princess Luna. After she asks forgiveness for her wrongdoing, the episode ends with a celebration in honor of Princess Luna's return. (And the entire reason Luna had turned to villainy in the first place was because she thought the ponies didn't love or respect her.)
You Are Not Alone: Twilight is facing Nightmare Moon alone, and the only thing that's capable of stopping Nightmare Moon was just shattered to bits right in front of her... then her friends come to her rescue...