The film's climax shows Emmett Dalton being killed in a shoot-out during an attempted bank robbery in Coffeyville, Kansas. In reality, Dalton survived the shoot-out and went on to write the book that this film was based on.
Just as Bob Dalton jumps on the stagecoach from the large rock, the coach driver flinches before he even sees Bob jumping on him.
In one scene near the end, one of the townsfolk refers to Oklahoma as a state, "...not in this State." Oklahoma only obtained Statehood in 1907, long after the Daltons' demise.