An Ounce of Prevention - S6-E13
Corrected entry: As Roy and the stagehand are bringing in the equipment to treat the shock victim Engine 51 rolls into the scene. Not enough time has passed for the engine to respond. They haven't even started treating the victim yet.
Correction: First, Cap and other guys at Station 51 were watching the live TV show, then heard the explosion happen live, so Engine 51 rolled out immediately and notified dispatch. Second, we don't know how far the set of the Tom Jensen Show is from Station 51. It cannot be a plot hole since we don't have the necessary information. All we know is Roy and John were cleared for 90 minutes. Third, when Jensen tells his live audience, "What you're witnessing is remarkable" John has already begun treating the victim with mouth-to-mouth resuscitation, while Roy and Jensen's guy go to wherever Squad 51 is parked outside, to get the stowed paramedic supplies. Then the shot dissolves (we don't know how much time goes by - 2, 3 minutes?) and cuts to Engine 51 arriving on scene, as Roy and Jensen's guy return with all the gear.
Super Grover ★
Engine 51 cannot just roll out since they saw it live. If they were the closest to the show, they would need to be dispatched to the fire. As we don't know where the show is, there may be another station closer.