Other mistake: The clock shows the time as 2:20. Ozzie goes outside and spends five minutes talking with Mr. Thornberry. When Ozzie comes back inside, the time on the clock is still 2:20.
Other mistake: Harriet phones a plasterer to repair a wall in the boys' bedroom. He says he will be there the next day. Ozzie phones Mr. Baxter and asks him to replace a broken rain gutter. Baxter comes to the house and tells Ozzie he has two big jobs to finish and "it will be about a week" - but he shows up the next day, same as the plasterer.