At the beginning of the movie, we see Craig draining the oil from a car. He unscrews the sump plug and black, used motor oil flows from the sump. In the next shot, from another angle, the oil continues flowing, but it's visibly new, clear motor oil.
When Vince is challenged to hold his breath, after Craig speaks to Audrey on the phone Colin announces that Vince's time was 1 minute, 59 seconds. Later, when Vince asks what his time was, Colin says his time was 1 minute, 58 seconds. A difference of one second is significant in the context of the challenge.