Bradford Dillman, who played Capt. McKay in the previous film _The Enforcer_, seems to be playing the exact same character here, except he's named Capt. Briggs. Even more confusing is that Briggs was the name of _Hal Holbrook_'s ill-fated lieutenant in the second Dirty Harry film _Magnum Force_.
When the young uniformed officer is shot during the bank robbery, he reaches to the left side of his forehead. Later, in the police station, he is seen with a bandage on the right side of his forehead.
While Harry is nailing up the targets, his shoulder holster has some sort of odd cross strap; as if someone in wardrobe just pieced it together. Moments later, while waiting for Horace to walk up on him, Harry's shoulder holster is the traditional Bianchi shoulder holster configuration - a single elastic strap around his right shoulder.
When Mick falls on the unicorn, there are three quick shots of him being impaled. The first and second shot show him straddling the unicorn with his leg straight. The third overhead shot shows his leg wrapped around the brass pole.
As Horace exits the car while visiting Harry, who is about to begin target shooting in the woods, one of the Panavision cameras is clearly visible, reflected in the car window, as well as Eastwood's son, who was visiting the set.
When Jennifer visits her exhibition and approaches the woman in the purple dress, reflections of two male crew members can be seen in the acrylic glass on the right, one of which quickly kneels to hide from the shot.
When Mick uses Spencer's (Sondra Locke) pistol to kill the chief. The other criminals are aghast. Mick claims it's a freebie. But he uses his bare hand to fire the weapon, leaving his fingerprints all over it. As a criminal in today's world, his prints are surely on record. So he's not only framing her, but himself as well.
The movie ends at the merry-go-round. As the credits start and the camera pulls out, the roller coaster and the merry-go-round are far away from each other. It is impossible that a person could fall from the roller coaster and crash through the roof of a construction that far away.
When Callahan is attacked by the four Mafia hit men, they start firing at a wooden box they suppose Harry is hiding in. One of them fakes shooting a pistol, mimicking the recoil, as it is clear that the gun doesn't fire at all.