Zorro’s Fighting Legion is a 1939 Republic Pictures serial featuring Reed Hadley as Zorro. The plot revolves around Zorro’s alter-ego’s (Don Diego‘s) fight against the evil Don Del Oro, who wants to become Emperor of Mexico.
An occasional trope in this serial is the ritual death of at least one native informant, much like the death of a red-shirted Star Trek Away Team newbie. The direction was identical for each snitch’s demise, creating a source of unintentional humor: each one, upon uttering the phrase, “Don del Oro is…”, is shot by a golden arrow and dies before revealing the villain’s true identity.
Here’s Chapter 2, Flaming Z. (0:15 mins)
This video is a version of the public domain file at Archive.org with cleaned-up audio. Description via Wikipedia.