Continuity mistake: In the scene in the airport after Maverick quits, Charlie tells him, "you've got that maneuver down real well," and it cuts to a close-up of Maverick. Movement is seen in the shiny wall behind him, which is a reflection of Charlie standing up. It cuts to a wide shot of both of them seated. Then she stands up to say, "So long, Pete Mitchell."
Chosen answer: The term "Ghostrider" refers to the squadron name. There used to be a Tomcat squadron called the Ghostriders. Usually in a radio call, the squadron name is followed by a number. For instance, in the first fight where we see Cougar get into a spot of trouble with the Mig on his tail, he radios "This is Ghostrider 117 this bogey's all over me, he's got missile lock on me, do I have permission to fire?" That is normally the correct term as to who is on the radio.