Continuity mistake: Flight scenes and especially dog fights seem to have no continuity at all. Altitude changes from scene to scene between extreme low-level to altitudes above 10,000 ft. and back. Airwolf's weapon bays are open, then closed, etc.
Continuity mistake: Airwolf goes from normal flight to combat mode and back several times per episode when it's supposed to be in passive flight.
Airwolf (a.k.a. Shadow of the Hawke) - S1-E1
Continuity mistake: When Stringfellow and Dominic first board Airwolf at the Libyan base, String gets in on Airwolf's right side, and pilots from there. When they land to rescue Gabrielle in the desert, he is in the left hand seat as the chopper lands and gets out of the left hand side.
Airwolf (a.k.a. Shadow of the Hawke) - S1-E1
Continuity mistake: When Hawke lands the helicopter during the film shoot, you see that the person in the left seat is handling the controls of the chopper normally, left hand on the collective, right one on the cyclic. In the next shot, the actor in the police uniform, sitting in the left seat, hides his face behind his arms and does not touch the controls at all.
Airwolf (a.k.a. Shadow of the Hawke) - S1-E1
Continuity mistake: In the courtyard of the palace, String has the weapons activated. A moment later, the gun pods are closed, then open again.
Continuity mistake: When Dominic is driving to Airwolf, in the long shot, he has shades. In the closeup, he doesn't.
Continuity mistake: When Hawke is first seen running on the ranch, his shirt is intact. A moment later, it's torn on the back, and the sleeve is ripped off.
Continuity mistake: When String and Dominic first look at Airwolf, the cockpit is dark. When they get out of the jeep, the cockpit is lit up with a greenish light.
Continuity mistake: When String tells Dominic about his plans to act on the phone call, Dominic says that things had been quiet for two months. When they're proceeding from liftoff in Airwolf, he said that three months hadn't harmed her, referring to Airwolf.
Continuity mistake: For most of the flight shots, Mace is shown in the right seat. Part way through the chase, he's shown in the left seat, and everything is reversed.
Continuity mistake: Just as Santini lands his helicopter after his rear rotor was destroyed, Hawke gets into his jeep and drives off. The number plate (licence) is reversed and Hawke's steering wheel is on the right side like British vehicles are. The next shot you see the shot has been flipped the correct way with both plate and steering wheel on the left side. (00:24:14)
Continuity mistake: During the final battle Airwolf shoots a Bell UH-1. In the following explosion shot a Hughes OH-6 is blown up.
Answer: I don't think it's ever explained why Mac refused to tell Hawke where St. John is.