During the drive up to Duncan's house, Clare makes reference to a "Victorian phone box". The first public telephones in the United Kingdom were not installed until the 1920s, long after the end of the Victorian era.
When Maddie complains about Jonathon's typewriter's lack of a letter 's' she says it's the most common letter in the English language to which Jonathan replies it's the 8th - it's actually the 7th after E, T, A, O, I, and N.