When Roslyn and Perce are behind the bar, sitting near an old car and a pile of beer cans, the cans change places from cut to cut when seen from behind them.
When Gay is seeing Susan off at the train station, she is supposed to be traveling east to St. Louis, but the train she boards is heading west.
When the rodeo PA announcer introduces Perce Howland (Montgomery Clift) on a bucking horse, he says Howland is from "White River, Wyoming". Howland corrects him with a shouted "California, not Wyoming". This reinforces Howland's remark at the pay phone that he was trying to call home, but the operator kept giving him Wyoming rather than California. When Howland later mounts a Brahma bull, the PA announcer says, "Perce Howland of Black Hills, Colorado." Perce said he recently had been in Colorado, so the confusion of origins is understandable and perhaps intentional.
When the truck starts to chase the mustangs, there are ten tires on the bed of the truck, five on each side. When Perce and Gay each rope their first horse and the tire attached to the respective lariat is slid off either side of the truck bed, there are then only six tires, three on each side.
When Guido talks about a star in the sky, the camera cuts to a shot of a pitch-black starry night. But the horizon behind the actors for the rest of the scene clearly shows that the sun is still shining.
As Roslyn and Gay are leaving the dry lake bed, they stop at the aircraft to retrieve Gay's dog. Roslyn jumps into the truck and slides to the middle of the bench-style seat with the dog jumping in behind her. Although Roslyn's hands are down by her side and the dog is between her and the door, the door slams shut. This obviously is due to a crew member closing the door right after the dog jumped in.
When Gay is holding the flashlight for Guido as he works on the plane, the flashlight is clearly off. Yet Gay keeps adjusting it as if to light the part of the plane engine Guido is working on.
When the truck is making sharp turns on the dry lake bed, the sound of tires squealing on asphalt is heard, not sliding on dirt.
When Guido is herding the horses down the canyon with his fixed-wing plane, there are aerial shots of the horses galloping down a two-track. The takes are shot directly behind the horses, and the plane is flying at the same rate of speed as the horses. A fixed wing aircraft couldn't fly slow enough to match the pace of galloping horses.
When Gay, Roslyn, and Perce are standing in the back of the truck watching the horses with the binoculars, the clouds behind them change with almost every scene ... from none, to one, to many. All this takes place in about 30 seconds.
The chase truck has no windshield. Also, while the two men riding outside on the flatbed are buffeted by wind, Guido and Roslyn barely see a breeze.
When Guido is chasing the horses with the biplane, he pulls up a shotgun, points, and supposedly fires it. While there is a sound effect, the gun itself does nothing - no smoke, no movement, nothing.
When the group gets ready to leave the house for the rodeo, as Gay says, "Honey, when you smile, it's like the sun coming up", directly under his chin an open doorway can be seen. Just inside this doorway, a bushy-haired crew member is visible, and he moves quickly to the left in an attempt to get out of the camera shot.
When Perce falls backwards into the lumber, a shadow of the boom microphone is visible on the ground beside him, and then it is seen moving as Gay and Guido help him up and into the house.
When Isabelle and Guido visit Gay and Roslyn in the desert, Gay greets Isabelle as "Thelma". The actress portraying Isabelle is Thelma Ritter.
When Gable, Monroe, and Clift look at the horses in the distance with the binoculars, all three of them hold the binoculars upside down (but they still work, of course).