No, objects other than the scoring golf balls may not be inside the scoring jugs. The inside of the scoring jug may not contain any objects, excluding scoring golf balls, throughout the duration of the run.
Immediate is not specifically defined in a tenth of a second or seconds so as not to put a burden on the Event Supervisor for timing. It is up to the Event Supervisor to determine the definition of "immediate". A team should not take chances of the ball taking more than 1-2 seconds.