Nash takes 3 shots at the helicopter. On the second shot, he takes out the tail rotor. As he delivers the third shot, the tail rotor is now in fine condition.
The car painted red with the white stripe that gets blown up with the blue car is obviously not the 74 Gran Torino. It has fins in the back.
While in the castle, Starsky and Terry are in the room looking at the headphones and the picture of Terry's wife. There is a shadow of a boom mic moving around on the wall behind them.