Steve uses a peephole in the front door to determine Francine's surrogate parents are visiting. However in any opening theme Season 4 and afterward, you can clearly see there is no peephole as Francine kisses Stan every morning.
In the opening sequence, when Stan picks up the newspaper, the headline is missing.
When Stan visits Francine's birth parents in Hilton Head, SC, he is shown riding with them along seaside roads on the sides of mountains, and surrounded by numerous hills. Hilton Head is a low lying area with no hills or mountains and an average height above sea level of less than 20 feet.