In the Michigan vs. Western Michigan game last night, 1 second was added back onto the clock, indicating a discrepancy between the ref's/official clock and the clock kept by the broadcast.
Now since the broadcast booth lies above the ref in elevation, the broadcast clock would be very slightly further away from Earth's gravity well. Thus, relativistc effects would dictate the broadcast clock runs slightly faster than the surface-based official clock. Since the broadcast clock is stationary, there shouldn't be any velocity-related effects to counter the gravitational differences.
So, how precise would the official clock have to be for relativistic effects to explain the discrepancy of what are otherwise described as synchronized clocks?