When the old jeep is being hoisted by a crane you can see its tires appear to be full and in reasonably good shape, as opposed to the rest of the vehicle. After 20 years they should be totally deflated and rotted, even in a desert.
When Wyatt is supposed to be in the airplane that crashes, there is never a splash in the pond prior to the crash.
When Logan is ambushed by 3 Feds and after he kills first 2, the computer shows Carson's dot running away, but when the scene switches back he hasn't even got up from being shot yet much less moving away. It's several seconds later when he starts running.
Rip Torn's character Sheriff Well's shows Kristofferson's character Logan a picture of Wells and someone purportedly Logan's father, suggesting they came up in their careers about the same time. Rip Torn was born in 1931 and Kristofferson was born in 1936, so they are only 5 years apart.
The film is supposed to take place in Texas but there are numerous scenes where saguaro cacti is visible. Saguaro don't grow in Texas.
While supposedly in San Antonio-- mountains are clearly reflected in the windows of a store.