In Firefly (episode: train job), Mal gets in a bar fight because he was a Browncoat. He gets thrown out of the bar, and the gang he was fighting follows him. They were about to kill him when Wash brings serenity up and tells the gang to leave, unless they want to get blown up.

"Every man there go back inside, or we will blow a new crater in this little moon."

The gang leaves, and Jayne laughs and says

"Damn yokels can't even tell a transport ship ain't got no guns on it. (laughs)"

but then, in Serenity, mal says

" Jayne, you and Wash hoist up that cannon mount. Goes right on top."

I know that in Serenity, some time has passed since the last episode of Firefly. Is there any canon evidence (like from a comic book, or something Joss said) that explains why they suddenly have a cannon?

  • 7
    You're quoting the line that's Mal instructing his crew to install the cannon. So it shouldn't be a surprise that it wasn't already installed beforehand. Sep 25, 2016 at 20:12
  • Is the cannon canon?
    – Rand al'Thor
    Dec 4, 2022 at 15:15

2 Answers 2


They attach it during Serenity, when they go into Reaver space.

During the final act of the Serenity film, the crew disguises Serenity as a Reaver ship, including attaching corpses to the hull and painting it in fake blood.

enter image description here

As part of this effort, they take a cannon from the colony Shepherd Book was staying. Presumably it's for defense in Reaver space, though they also use it to "get their attention" later and inspire the Reavers to chase them.

Here's the sequence showing exactly where the flack cannon came from:

Mal running toward cannon and Book
Mal running toward cannon and Shepherd Book

Book dying on the cannon's sandbags
Shepherd Book dying on the sandbags of the cannon

The crew attaching the cannon to Serenity
Serenity crew preparing to attach the cannon to the top of Serenity

Here's a a high-quality image that makes it clear that the cannon on Serenity in Reaver space is the same one from the planet. Also note the tie-lines and braces, from the quick-and-dirty job of attaching it to the hull. enter image description here

Fun Fact: The prop used in the film is actually a genuine World War II-era German Flak 30/38 20mm anti-aircraft gun.

  • @CreationEdge Thanks! I spent a while looking for those exact pictures, but I couldn't find them. That scene is full of super-generic terms: "serenity" and "book" and "cannon" and "ship". Hard to specify what you're looking for in a search. :P
    – Nerrolken
    May 6, 2015 at 18:55
  • 1
    I used serenity shepherd book "cannon" and serenity shepherd book turret. I think for one of them I had to use -firefly to stop getting generic pics of Shepherd from the show.
    – user31178
    May 6, 2015 at 18:57
  • 1
    Second-last picture, "Serenity crew preparing to attach the cannon to the top of Serenity". Isn't that in fact from the end of the film, dismounting the cannon? Jun 20, 2015 at 18:19
  • @Peter's right. Sep 25, 2016 at 20:13
  • yeah, I think i must have been half asleep or something when I first watched 'Serenity' Jan 10, 2017 at 21:42

According the the film's official novelisation, the cannon belonged to the community of Haven where it was used as a civilian defence tool;

Sadly, the town proved a powerful reminder to Mal of Lilac—several shacks, not as ramshackle as on the other moon, but indicative of the same hard living. They also had a church, which got more use nowadays, and a smal vegetable patch, which was another of Book's contributions to the community.

One thing they had that Lilac didn't—and could rightly have used—was a large cannon, salvaged off a warship some years back. It was the main thing that kept Haven living up to its name.

Dozens of townsfolk came out to greet them, including Doane, who had cannon duty today. He jumped down from the chair that had been attached to the cannon and gave Mal a hearty handshake. Little Hiroko ran toward them at top speed, yelling.

It's also explained that this is the cannon that Book used to shoot down the raider.

Without another word, Book ran over to the cannon. Gently removing Doane's body and laying it on the ground al respectful-like, he then leapt into the firing chair and whirled it on the Alliance ship just as it finished raining down fire on the shepherd's own church and adjoining garden.

Though Bernabe didn't rightly recognize the specific class of ship, he was familiar with the design type behind it. Was fair similar to the Striker-class that the Alliance favored during the war. This was souped up beyond all good sense, but Bernabe figured the engine core was in the same place.

He knew this mainly because Book's first and only shot went right to the spot on the undercarriage where Bernabe reckoned the core was.

This is fully confirmed by the film's screenplay

It is a world of fire.

Every building burns, some blown right apart. Bodies litter the scene, not one of them moving. There's a grounded Alliance ship not far from the cannon that shot it down.


We see Mai's face as the sight hits him like a gut-punch. EXT. MINING CAMP - MOMENTS LATER The crew pours out even as the ramp lowers, going off in all directions, calling out to people...

Kaylee heads for the burning church.

shortly later...

MAL: Jayne, you and Wash hoist up that cannon mount. Goes right on top. Piece or two of the other ship, stick it on. Any place you can tear hull without inner breach, do that too.

(looking around) And we're gonna need paint. We're gonna need red paint.

  • 2
    Yeah, I'm not sure how you can hear "put it on top" and interpret that as it having been there already :-/
    – Rawling
    May 6, 2015 at 19:38
  • 2
    @Rawling I think OP's confusion was that he took moving the cannon ("hoist up that cannon mount") to mean that it was already on the ship, just in another location (like underneath).
    – Nerrolken
    May 6, 2015 at 19:39
  • @Rawling - In the hold, maybe?
    – Valorum
    May 6, 2015 at 19:46

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