On around 28 minutes in, the phone Harper uses to take the picture and the phone she uses to see it in the bath are different.
While Harper is being chased by Geoffrey in the car, you can see the wheels have different rims from the ones you see in the shot when he crashes the car into a stone wall.
Harper picks a red apple from the orchard, but when Geoffrey points to it on the table, it is mostly green.
Daffodils and Bluebells are visible which suggests that is Spring, but Harper plucks a ripe apple from a tree which only happens in Autumn or late Summer.
Harper spends time shouting in tones down a long tunnel, waiting for the tones to echo back so she can harmonize with them. But as the tunnel has no back wall the sounds would just continue away from her and wouldn't 'bounce' back.
Geoffrey comments on the view from the bedroom window, saying the church spire is visible. The church has a tower but no spire.
When James and Harper are arguing over her text messages, he tells her to unlock the phone, but the app screen is clearly visible.