Continuity mistake: When Walter is imagining himself killing his wife, the bed sheets change from silver to red momentarily after he wakes up.
The Number 23 (2007)
1 continuity mistake - chronological order
Directed by: Joel Schumacher
Starring: Jim Carrey, Danny Huston, Virginia Madsen, Logan Lerman
Factual error: Walter reads from his book he wrote in 1991. He mentions the Oklahoma city bombing. That didn't happen until 1995.
Walter Sparrow: Of course time is just a counting system... numbers with meanings attached to them.
Trivia: In an interview, Jim Carrey admitted to being obsessed with the number twenty-three.
Answer: A guess: it matched the colour of the walls that she had chosen (red). It's also shown sitting on the shelf, facing outwards, making it more obvious.