Continuity mistake: When Storm and Callisto are about to engage in combat, they are using staves that look like lightsabers, with the hilts at the bottom. When they start striking at each other, both staves now resemble a double-edged lightsaber, with the hilt in the middle. (00:18:25)
Answer: For one thing the engine running the pump isn't that loud. The characters have conversations at a normal volume without having to scream at each other. Even if the conductors could hear it, there is no reason they should care or be suspicious. It just sounds like an engine running in the distance and they don't care enough to look for what is making the noise. At that very moment there is also a kid riding a dirt bike in the area. Engine noises are a very common thing.
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