Anachronisms: Mockingbird calls are heard in a scene between Billy and Louise near the end. At the time the film is set (between the early 1870s and the late 1880s), the mockingbird range was entirely in the American South. There were no mockingbirds in Maine - not even in the year the film was made (by which time the mockingbird's range had extended to New York and New Jersey).
Anachronisms: As everyone leaves for the clambake in sailboats, we can see, for a full fifteen seconds or so, several men in one of the boats wearing very modern-looking caps and sunglasses.
Miscellaneous: At one point in the film the sun is shown to set over the ocean, although the film is set in Maine and the sun sets in the west, not the east.
Revealing mistakes: As Jigger (Cameron Mitchell) first talks to Billy (Gordon MacRae) about a robbery, the sound of an outboard motor can faintly be heard in the harbor.