Naturally, the ancient Bell reaches the ladder first, followed by the slightly less ancient Walter, and Peter starts fending off the zombies with his kung fu, also taking the time to untie the single knot tethering the zeppelin to the building. But as the zeppelin starts moving away, he's accosted by another zombie, and he's backed up against an air intake fan on the roof. So you know where this is going.
He takes down one zombie and throws the other into the giant fan, killing it more dead than it already is, and then he starts sprinting for the dangling ladder, and only has to jump about twenty metres off the side of the building to catch it, and the men are away.
While Peter futilely searches through a window with binoculars, Walter and Bell chill in the control room, or whatever the hell you call it on a blimp. Walter tells Bell that he should have known Bell had no intention of dying, that time they were over there getting Peter back, because Bell actually said goodbye. "As long as I've known you, you've hated goodbyes," says Walter. "I suppose that's true," says Bell, sounding not in the least interested.
Then Walter starts whining about how he needs Bell, because he doesn't know what to do about Peter or the machine, or how to get past this one level on World of Goo. Bell says when they were young and foolish and had too much power and too many dreams that no one could stand in the way of -- ZZZZZZZZZ. Oh, sorry. Anyway, he says they needed each other then, because back then they didn't have the wisdom of humility but they do now so the path Walter chooses will be just and I swear somebody better shoot somebody or somebody better turn into some kind of monster soon, because this half-baked philosophizing is turning me homicidal.
Then we see someone somewhere else cutting a hose, spilling amber fluid, and in the control room, the fuel gauge suddenly starts heading left with an alarm sounding. Peter comes in to ask what's up. "Fuel gauge," says Bell calmly, not at all like they're seconds away from running out of fuel. So Peter heads to the engine room, which he finds is chained and padlocked shut. There's also fuel spilling out from under the door. Fortunately... I guess?... the key to the padlock is hanging nearby, but no sooner has Peter freed the door when it's kicked open, knocking him down, and there's a dude pointing a gun in his face asking Peter how many of him there are. Peter says it's just him, and the dude tells him he's got a flare gun. "You don't want to get shot with a flare gun," he says, begging the question of whether you'd want to be shot with ANY gun.