When Joe Kidd is kissing Elma, Harlan's girlfriend, they are interrupted by one of Harlan's henchmen (Gannon). Elma turns her head to the right to look at him. In the next shot her head is turned to the left as she looks back to Kidd.
On a shot of Clint the priest is seen in the background coming out of the church. The next shot is of Lamarr crouching behind rocks and in the background the priest is coming out of the church again.
At the beginning of the film when Joe is lying on the cot in jail, Naco pours a coffee into a mug on the corner of the table, then proceeds to fill it again after asking Joe if he wants one.
Kidd fires the ten-round Mauser pistol twice: 14 rounds and about 22 rounds. In one or two sequences the hammer clearly does not function so the sound effect was added separately.
The church name is St. Paschal Bayon, and should be St. Paschal Baylon.
Some of the characters wear 1970s bat wing rodeo hats, especially Frank Harlan.
When Harlan's gang returns to Sinola, Roy tells the desk clerk at the hotel that there are eleven of them. However, in the gunfight, we see the deaths of seven (including Harlan) and the surrender of two more. Two have disappeared. Since seven are dead and two have quit the fight, it follows that the missing two have run away.
When the shootout begins in the village, one of the bad guys is shot in a doorway, and when he flies backwards into the room, the "brick" wall he lands against gives and then wobbles and shakes like rubber or cardboard.
In the early jail scene, after Joe Kidd throws the stew in Naco's face, he hits him with the empty pan. After the hit you can see the pan has no dent in it. Joe lowers the pan out of camera sight (you can hear it bump the table). When he raises it again, it has a large dent in the bottom. If you watch closely you can tell that he is changing pans out of sight of the camera.
Despite being set in New Mexico, the geography of the film is all wrong. Besides the geology being wrong, the vegetation is clearly not the type that would be found in New Mexico.
When Mingo shoots the man that Frank wants to question, he does so while standing directly next to his horse's head. Not only would that have startled the horse and potentially led to him being kicked, but it would also have damaged the horse's hearing, making it dangerous to ride.
A trained long-distance shooter would have never done that.
A trained long-distance shooter would have never done that.
When Joe Kidd bops the sentry in the head with the water jug on the church bell rope, he is wearing Lamarr's hat with the spare stripper clips for he Mauser pistol. After he knocks the sentry out, he switches Lamarr's hat for his own leaving the spare ammo stripper clips behind.
When Joe Kidd is in jail, he is handcuffed to a metal frame bed. When Naco asks him if he wants a cup of coffee, Joe reaches for it but is unable to reach the cup because he is handcuffed to the bed. The bed was a simple iron frame bunk and had no vertical support bars along the headboard. All he had to do was slide the handcuff along the top of the headboard and he could have reached Naco, yet alone the cup of coffee.
Near the end, when Harlan enters the rear of the courthouse, the railing that Bob was handcuffed to and ripped apart is now in pristine condition.
When Joe Kidd is approaching town after having joined up with Luis Chama, he sends Ramone to ride into town first to test if the area is covered by gunmen. As Ramone is falling off his horse you can see a vehicle driving across the frame in the distance, on the far left.
When Harlan tells the priest to order all the villagers outside, there is a jet contrail visible in the sky behind them.
Although the film takes place in the early 1900's the dress of many of the characters reflects a later time. The men's shirts button all the way down the front, several of the hats worn are of modern (1970s design) and the boots worn clearly don't match those of the period.
In several scenes outside the church after the 45 minute mark, there's a large jet contrail crossing the sky behind the actors.
The movie takes place in New Mexico, but saguaro cactus can be seen in the town (Sinola County) scenes. Saguaro cactus can be found only in the Sonoran Desert of northern Mexico and southern Arizona, with the thickest concentration around Tucson which is where those scenes were actually filmed (at Old Tucson).
When Joe Kidd and the townspeople are imprisoned in the church, the priest tells Kidd that today is the Feast of St. James. The Feast of St. James occurs on July 25. Throughout the film, it clearly is on the shoulder of winter (fall or spring) with the characters wearing heavy coats, and small patches of snow visible in the mountains around the desert.
The character of Joe Kidd says that he shot a buck mule deer "over south of Monero," and Mitchell says that's on the Jicarilla reservation. It isn't. South of what's left of Monero is not on the reservation; in fact, Monero is east of the reservation. In between Monero and Dulce (which is on the reservation) is a very small town, Lumberton. There is no way at all that Kidd could have been charged with hunting on reservation land if he were south of Monero.
At about 1:17:00 Right after they shot Ramone, a White Van can be seen driving through the background.
When Joe Kidd gets the drop on Luis Chama near the rural village and orders Chama's ruthless, cutthroat gang to ride with them to the Sinola jail, the gang members miss innumerable opportunities en route to shoot Kidd in the back and set Chama free.
When Harlan's men go into the church to get the first five sacrifices they don't notice Kidd is gone.
Frank Harlan's custom Savage 99 is a left-handed version, but Robert Duvall is right-handed and carries the rifle right-handed throughout the film.
Lamarr doesn't seem to understand that his Mauser's shoulder stock is to be put up to the shoulder to fire, not held in the armpit. On the other hand, Joe fires it correctly.
Near the end of the film when Joe Kidd and the sheriff are coming out of the courthouse, the sheriff tries to put his gun in his holster, but misses and has to try again.