An Ounce of Prevention - S6-E13
Continuity mistake: While John and Roy begin rehearsing in front of Marco and Chet, when John lights the flame his watch reads 10:00, but just a few minutes later when John puts the sawdust into the strainer his watch reads 10:30. When Squad 51 is dispatched to "sick child," timeout is 12:13, and after John and Roy get back to the ER the second time after searching the garage for the poison it's 1:05 at the ER. Then when they're on the Tom Jensen Show, as Roy tries to light the flame John's watch reads 11:30, but when he and Roy are treating the electrical shock victim, his watch reads 4:00.