While the time frame of the movie is later in the fall, a mother with baby ducklings are shown in a pond. At that age, they would never survive the winter.
During the reading of the will, Aunt Dee addresses her friend Ron stating that she has only known him for a couple of years, since he had moved there from the mid-west.
At 44 when the waitress sets down the glass she sets down the same glass twice so the orange one just magically sets its self down.
Movie set in fall, but maple sugaring is done in the spring. This is not a mistake.
At about 37 minutes in, Maggie tells her sister and brother-in-law that she wouldn't mind if they sneak in later to make her dinner. But, this line is clearly dubbed over. Her lips say "break in" instead of "sneak in."
In the last act of the movie, when Dex says, "She had the words, to the owl poem...", his mouth movements do not match the words.