Alice's diary says that November 13 was on a Thursday in 1967. It was actually on a Monday. The subsequent dates in the diary were also wrong but conducive to the initial error.
The dates in Alice's diary had the wrong days of the week but the newspaper had the right day - Thursday November 23rd.
The minibus in which Ruth is riding with the two students has a number plate with a 'K' suffix. This indicates a vehicle from 1971 not 1968.