In other episodes before and after, it is clearly established that the row houses have two bedrooms. In the next episode Elizabeth invites Opal to stay with her because she has an extra bedroom. Therefore it is very odd that Elizabeth and Rosemary prepared the sofa downstairs for Rosemary to sleep on.
Elizabeth Thatcher invites the boys to dinner stating she was making spaghetti. Spaghetti did not come to the US until the 1920's. It actually originated in Little Italy in New York City. Town folks in the west would have no idea what it was during this time period.