I've been listening to a bit of this lately. The story goes that on the plane most of the group decided to mix things up a bit and play what they called anti-music. That is, not play what might be expected at certain parts but play the opposite. They told Wayne Shorter right before the set what they were doing. They had second thoughts when they saw that they were going to be recorded but they stuck with the plan. They never mentioned it to Miles- he just rolled with it.