This occurs after the the 'we hung out' segue, scene with strip poker, and the scene where Calvin is first told by Hobbes not to go into the attic.
As part of the montage establishing Calvin hanging out with Hobbes during the first few days of moving in, we cut to him in a army outfit (that's oddly child-sized), complete with a Vietnam-style helmet that has some something written on it (probably some sort of parody of "Born to Kill", "Born to Murr"?). Calvin he holding his machine gun up, stalking through the woods surrounding the lake behind his house, he's nearly on the other side of the lake now, watching it between the trees.
Calvin (bringing up a big 70's walkie-talkie to his mouth from out of nowhere): Charlie-232, do you copy over?
Calvin glances over and we see Hobbes sneaking up behind a tree about 20 feet in front of him, he's also in the Vietnam-style commando outfit, complete with face paint and a flame thrower.
Hobbes (speaking into his walkie-talkie, peering out from behind the cover of his tree): This is Charlie-232, we have the target in sight. Over.
The camera pans to show that Calvin and Hobbes are both eyeing a group of ducks lounging by the lake.
Calvin: Commence aerial bombardment in 3...2...1...
The pair both jump out of cover and begin shooting at the birds, scaring the shit out of them as they go flying on all directions. Hobbes is burning a few to a crisp with his flamethrower while Calvin is firing his machine gun in all directions like a maniac, screaming various obscenities, after some of the dust clears they both catch their breath and begin laughing. We see them laughing from the lakeside and as the camera zooms in the audience sees they're in front of a house that slowly comes into focus. The camera continues panning and we see that a little girl is actually standing behind Calvin. The little girl is around eight years old, she's half-Russian, and she's eyeing Calvin curiously from her front porch.
Margo: I like your doll.
Calvin blinks and turns back, and when he does we see that he's no longer wearing the uniform and he no longer has the gun. He just has a badly-chewed and dirtied tee-shirt and shorts and the stuffed tiger toy dangling out of one of his hands. He looks down at it for a moment, as if needing to regain his bearings after the abrupt shift back into reality.
Calvin (uncertain): Thanks...
Calvin (cont'd, looking over the dilapidated house, it's quite ugly): You live here?
Margo (nodding, pointing): And you live across the lake.
Margo (cont'd, answering Calvin's puzzled expression): I saw you moving in. That house is haunted you know.
Calvin: I know.
Margo: The woman who lived there killed herself.
We see Calvin stiffen despite himself, he doesn't like being reminded of his mother's suicide. But Margo doesn't seem to notice, she's just a kid (and more of a real kid than Calvin) after all.
Margo: What's your doll's name?
Dialogue is kind of weird here, needs improvement.
Calvin: "Hobbes." And he's not a doll. My mother gave him to me.
Margo: I have a friend like that too, my dad bought him for me.
Margo (cont'd, picking something up and running off the porch to Calvin, stopping in front of him, proudly holding out the stuffed animal with both hands): Peter Wolf!
Note that Peter is also her father's name and a pun on "Peter Wolf".
The stuffed animal is a badly worn wolf, very badly worn, it looks like it desperately needs a wash. Calvin reluctantly takes it in his hands, examining the odds stains.
Hobbes (coming up from behind Calvin, out of nowhere, examining the stuffed animal thoughtfully): Hmm, it looks like "Peter" has seen better days...
There's more conversation where Hobbes makes some comments on Margo, he likes her, but he also points out some troubling signs of abuse in her house, also mentioning that Rosalyn said Margo's father was a dick. Margo makes comments about Chance, who Calvin hasn't met yet, and the comments are rather ominous. Although at this point Margo already knows Chance, he was attracted to her, like Calvin, and Chance wants to use Margo to his own ends.