Factual error: Lynette's neighbor tells her that the pot Lynette's sons gave her is really hers, the neighbor's, and she bought it in Costa Rica. She turns the pot over to show Lynette that the price is marked on the bottom, with a number followed by the letter p. One supposes that the p might stand for peso, except that the currency of Costa Rica is the colon, which consists of 100 centavos. No p in sight.
Continuity mistake: At one point in episode 1.2 ("Ah, But Underneath"), Susan looks at the note used to blackmail Mary Alice and we can see that it has been folded twice and become somewhat crumpled. Two episodes later in "Who's That Woman?" (1.4) when the girls show the note to Paul, it is almost perfectly smooth with a single horizontal crease.