Or the laser reflectors?
I was hoping someone would mention that.
Additionally, there is the matter that the comms were monitorable by hams equipped with sufficiently robust equipment - if they didn't orginate from the lunar surface, but instead were transmitted from lunar orbit, then they would exhibit Doppler drift, and would have gone out of range everytime the capsule went behind the moon.
Neither effect was observed by hams, or else they would have reported the anomaly. And so would the Russians, who had every reason to want to debunk a faked American space acheivement.