Revealing mistake: In the scene directly after an Indian attack, we see four dead Indians on the ground covered with blankets. The first Indian's blanket is removed to reveal his face and it can be seen that the "dead Indian" is alive and breathing. The blanket over his stomach is moving.
Rio Grande (1950)
1 revealing mistake
Directed by: John Ford
Starring: John Wayne, Ben Johnson, Maureen O'Hara, Claude Jarman Jr.
Factual error: The cavalry sing Low Bridge (or Fifteen Years On The Erie Canal) as they trek across Texas in 1879. This was written by Thomas S. Allen in 1905 during the time the Erie canal was switched from mule power to engine power. (00:49:00)
Mrs. Kathleen York: Aren't you gonna kiss me goodbye?
Lt. Col. Kirby York: I never want to kiss you goodbye, Kathleen.