During the mustang quartering scene, after Croyden is cut free, he and Randolph ride past the same unique rock formation twice as they try to stop the horses (dark vertical stripe or shadow).
John Payne (I)'s Capt. Croyden character and much of the cast are armed with .45-cal. Colt 1873 SAA "Peacemaker" revolvers. The story is set in 1863, a full ten years before the model was introduced by Colt. The handgun a Texas Ranger and a Union Army officer should be carrying would more than likely have been the Colt 1860 Army, a Civil War-era "cap-and-ball" pistol, yet the gun belts worn by the actors have bullet loops full of .45-cal. "Long" Colt cartridges.
Really bad spy-craft to start with a visit to the grave of the last agent sent there when they know the bad guys have spies all over the place. Big risk of raising suspicion for no worthwhile intel gain.