the aliens were being entertained at a party thrown by the govment, if any of the folks at the gate had gotten on the base, it is not likely that they would have actually got into the party room, as the party was by invitation only. If your name was not on the list, they would not let you in.
Concerning the female that was apprehended at the gate and detained, she was given a party room pass and is shown towards the end of the video.