As Terence Stamp applies makeup for his circus act, an edit shows the half-finished lines drawn on his face, but the subsequent shot shows him applying the lines that were previously there already.
The Valentine's Day greeting card that Bathsheba sends to Mr. Boldwood is of a contemporary 1960s style.
During the "pie in the face" circus scene, the cream is piled on contemporary 1960s white paper plates with fluted edges. Disposable paper plates were invented in the early 1900s. The movie time frame (which differs slightly from the book) ends around 1868.
At the wedding party at the end of the film one of the band members is playing a sousaphone, which wasn't invented until around 1893.