The church service takes place in the evening but when Jackson, Helen, and Martha return to the farmhouse, it appears to be daytime in the kitchen. The same thing occurs when Helen is talking to Martha in the kitchen late at night while Jackson is sleeping on the couch.
Helen and Jackson get married and then return to New York. This whole time the couple is in New York, Helen is not wearing her wedding ring. When they return to Kilronan, she is wearing the wedding ring. This maybe suggests that the filming in New York took place before they shot the wedding in the country.
When Helen goes to the barn and finds the locket in the drawer, Martha catches her. When Helen hears Martha, she closes her hand around the locket above the open drawer. In the next shot, every drawer in the dresser is closed.
At the end of the film, Jackson slaps his mother Martha to the floor of the kitchen. Martha falls in the middle of the floor. In the next shot, she is over by the stove with one arm over the door handle. A moment later she is back in the middle of the room.
Martha attempts to induce Helen's labor by spiking a cake with Oxytocin. We see Helen eat the cake, and then several hours later go into labor. The problem is that Oxytocin is broken down in the gastrointestinal tract and rendered ineffective. It needs to be injected or inhaled to work.
When Helen and Alice are at the retirement home feeding ducks, the shot pulls out and you can see the ducks in the pond at the bottom of the screen. They are swimming in backwards circles suggesting the shot was originally moving in, not out and was reversed.