While the astronauts were en route to the pad, three men were working on a hydrogen leak on the Saturn V.
Launch control narration:
"This is Apollo Saturn Launch Control; T minus 2 hours, 40 minutes, 40 seconds and counting. At this time, the prime crew for Apollo 11 has boarded the high-speed elevator from inside the A level of the mobile launcher which is the second level inside the launcher. This is the high-speed elevator; 600 feet [180 metres] per minute, which will carry them to the 320-foot [98-metre] level, the spacecraft level. Shortly, we'll expect astronauts Neil Armstrong and Michael Collins to come across Swing Arm 9, the Apollo access arm, and proceed to the White Room and stand by to board the spacecraft. The third member of the crew, astronaut Edwin Aldrin, will be the last one to board the spacecraft, will stand by in the elevator seated in a chair while his two comrades first board the spacecraft. Once Armstrong, who sits in the left-hand seat, and Collins, who will sit in the right-hand seat during lift-off are aboard, then Aldrin will be called and he will take his seat, the middle seat in the spacecraft. The spacecraft commander Neil Armstrong and the Command Module Pilot Michael Collins now proceeding across the swing arm into the small White Room that attaches at the spacecraft level. In the meantime, about 100 feet [30 metres] below, we have a technician - a team of technicians working on a leaking valve which is a part of the Ground Support Equipment, a part of the system that's used to replenish the fuel supply for the third stage of the Saturn V rocket. He is proceeding to tighten a series of bolts around this valve in the hope that this will correct the leak. Once the technicians do depart, the hydrogen will again be flowed through the system to assure that the leak has been corrected. The spacecraft Commander Neil Armstrong and CMP, the Command Module Pilot Mike Collins, now standing by in the White Room. T minus 2 hours, 38 minutes, 45 seconds and counting; this is Launch Control."
Leak corrected but now issue with a radar?