When Ted removes his tie, his collar jumps from buttoned (closed) to unbuttoned (open).
When Sylvia is crying, towards the end of the film, she raises her hand to her face in one shot, but immediately following this both hands are in her lap.
The movie depicts Aurelia Plath meeting Ted Hughes for the first time after he married Sylvia Plath; in reality, she had attended their wedding.
The film begins with the time that Sylvia and Ted met, and the trees are shown in autumn colors with falling leaves. However, Sylvia Plath and Ted Hughes met in late winter, February of 1956, when the trees would have been bare.
When being connected to a call you used to press button A. You only pressed button B when you were unable to get through and that enabled you to get your money back.
When Ted and Sylvia are in bed together and she is discussing her suicide attempt, you can clearly see Daniel Craig's tattoo through the make up on his shoulder and Gwyneth Paltrow's hair net to which her wig is attached.
Ted is already wearing a band on his left ring finger when he asks Sylvia to marry him.
Using the telephone box, Sylvia fails to "press button B" before speaking.
The American scenes are filmed in and around Dunedin in New Zealand where traffic drives on the left-hand side of the road and the vehicles are all right-hand drives. In the scene after Ted Hughes has admitted his first infidelity, Sylvia Plath walks out into the rain and gets into the car which is clearly American and has a left-hand drive. But the other vehicles in front, seen in silhouette, while all seeming American, are all right hand drives.
When Ted says "It reminds me of my days in Mytholmroyd" he doesn't pronounce it correctly, saying "MITH-um-royd" instead of "MY-thum-royd".
The important character of Alfred Alvarez, the literary critic who befriended Sylvia Plath and championed her work, has his name pronounced throughout the film by all characters in the American manner, that is, as "ALVAR-ez". In fact, the real man pronounced his name in the European way, as "al-VAR-ez".