There are parts of the dialog which are going on in the background but are masked out by on-screen dialog or music. However if you have a Dolby Surround/Pro-Logic system you can probably hear them a little easier.
Garbage-men Scene Part 1
Just as Art runs out of his house and jumps over Ray's hedge you can just make out:
Joe: "This could be the key to..."
Vic: [Shouting at Joe about "the key to" and "you need help"]
Garbage-men Scene Part 2
When Bonnie spots Queenie on the lawn you can hear this in the background, it's a direct continuation from "they must have switched on us during the night":
Art: "Ray, there's nothing in here. We practically checked this whole truck. They must have switched on us during the night."
Joe (Garbie #2): "The FBI?"
Art: "No, the Klopeks"
In the trailer that's on the DVD you see Art say "Klopeks" whilst he's in the back of the garbage-truck.
There is then some further dialogue between Art and Joe which is mostly inaudible and then you hear:
Art: "Do you honestly think that...?
And then whilst Bonnie picks up Queenie, we can faintly hear Ray starting to tell of what he saw the Klopeks doing the night before.
