Numerous shots of the booster show a Saturn 5 instead of the Saturn 1-B that was actually used for the flight.
When Walter Schirra and Deke Slayton are being filmed by the TV crew while fishing on the beach, the frontal part of the brim of Slayton's hat is sometimes up and sometimes down in subsequent shots.
Its flipping up and back down because of the wind, which can be seen in the shot when the 'director' says " that's fine, that's fine " about time 17:13-17:15.
When the weather station chief is being interviewed, the clock behind him does not move, not even the seconds hand.
When discussing Wally Schirra's concerns about the wind, Deke Slayton said that, if Wally wanted a hold, he could have one. That would not have been Slayton's right to make that statement. Only the flight director for the launch could do that. Slayton headed up the astronaut division. At most, he would have been able to make a recommendation to the flight director.
The documentary filmmaker is wearing an earring. In the late sixties this was unheard of.