The funeral scene. The fact that even Jayne looks like he's about to break down says something there.
Or when Mal asks Zoe about the repairs near the end. With a look of heartbreaking stoicism, she replies "She's tore up plenty, but she'll fly true."
Also, Mal's final monologue to River. "Love keeps her in the air when she oughta' fall down."
Book's death scene hits hard. Especially the final exchange:
Book: You can't order me around, boy. I'm not one of your crew. Mal: Yes you are.
Book: I don't care what you believe... just believe it.
Every friend, every accomplice, every man, woman and child who ever supported Serenity's crew—dead. The fact that the Operative, of all people, seems to regret this just hammers in the tragedy.
The Operative:I'm sorry. When your quarry goes to ground, leave no ground to go to.
The Operative's speech to Mal after he organizes the attacks on the crew's allies. The way he enunciates, "I'm a monster," is distressing, to say the least.
River's disjointed breakdown on Miranda, like a lot of the scenes involving River in this movie, is jarring and emotionally hard-hitting, especially the bit at the end where she starts praying frantically in Chinese. In the midst of the chaotic, disjointed Chinese prayers, she suddenly breaks into English long enough to scream.
River: Please, God, make me stone.
River's ramblings while locked in the supply closet with Simon. It doesn't become apparent just what she's saying for a bit, but then you get her laughing/sobbing comment about "Bullet in the brainpan, squish." and you realize she wants to commit suicide rather than let the rest of the crew be in danger on her account.
When River breaks down after Simon hears her mention Miranda. Fridge Brilliance when you remember that her conditioning at the Academy was while she was asleep and while she is sleeping she seems to dream often of the Academy and the Reavers. Who blames her for not wanting to be put to sleep.
River:[crying] It isn't mine! The memory, it isn't mine, and I shouldn't have to carry it! Please don't make me sleep again...
River: I don't know what I'm saying. I never know what I'm saying!
Mal's and Inara's exchange after the fight at the training house.
Inara: You came to the training house looking for a fight.
Mal: I came looking for YOU.
Inara: I'm not trying to tear you down!
Mal: But you fog things up! You always have. You spin me about. I wish like hell you was elsewhere. [storms off]
Inara: I was.
When Simon gets shot. He's lying there thinking he's about to die and he turns to River and starts apologizing that he won't be able to look after her anymore.
"My bag." *THWACK*
Mal stumbling back out to the rest of the crew after sending the message. The way his voice cracks when he asks about River... From the second Mal kicked open that box, he cared about her and what happened to her. No matter how much he whinged about her and her prissy brother.
When watching the report from the doomed doctor about what happened on Miranda, Wash is the first to realise the truth: "Reavers. They made them." The horror and disbelief on his face is heartbreaking. The actual report itself, really shows how not all of the Alliance was evil and corrupt and makes the death of the woman and the implication that it was a slow gruesome death all the more horrifying.
Somewhat fridge, but remember when Wash and Zoe joke about her getting a "slinky dress" in "Shindig"? It's what she wears to his funeral. Unless you take on the interpretation that it was her wedding dress-note because what other white dress would someone like Zoe have? which just makes it so much worse''.note Possibly mitigated by the strong Chinese influence on the series; in China, white dresses are more associated with funerals than with weddings.
"I am a leaf on the wind. Watch how I—" Harpoon. Dead. Zoe's reaction. At first she shuts down emotionally but by the fight with the reavers she seems to have gone full death seeker, walking in their lines firing a shotgun and then screaming and stabbing a corpse over and over until she's injured and the crew drag her back.
The final scene with Mal and River in Serenity's cockpit, doubly so because it's probably the last time we'll get to see any of these wonderful characters onscreen.
Even the Operative gets one. After he sees the video, he's just sitting there catatonically, his eyes full of tears. He then abandons his mission and lets the crew go.
A bit of Fridge Tearjerker for the Reavers: They have the reputation in the 'Verse as being violently insane, and even those who don't believe they exist have heard the stories that gave them that reputation. So why, the question is asked, haven't they already wiped themselves out from infighting? Because they're not always that violent; the movie shows that their specific brand of insanity is a result of anger taken Up to Eleven, and they're not angry at each other. Whatever remnant of humanity in their souls allowed them to hold onto enough brains to fly scavenged ships and set up traps and ambushes, also allows them to recognize each other for what they all really are: the last surviving victims of a planet-wide genocide. This could also explain why they send out raiding parties, carving a bloody path across the rest of the 'Verse. They're trying to take vengeance on whoever was actually responsible for that terrible crime, but they're perpetually frustrated by not knowing who that is... and every living person they encounter along the way, reminds them of what they've lost.
