Susan gets Eli to change the locks after Karl leaves her, but in Season 2 he lets himself in and tells Julie that he still has his key.
In a flashback scene that takes place the very next day after Susan learns her husband Karl cheated on her with his secretary, Eli Scruggs accidentally informs Susan that Karl cheated on her with more women than just the secretary. However, in the 11th episode of Season One, which chronologically takes place almost a full year after Susan and Karl's divorce, and therefore chronologically takes place after the scene with Eli, it is a major plot point that Susan learns that Karl cheated on her with more women than just his secretary.
Eli is shown to be the last person talking to Mary Alice, who has the blackmail note in front of her and shoots herself after he leaves. However in the Season 3 episode 'Bang', Lynette has nightmares as she saw Mary Alice getting the note from the post and going into her house, and shooting herself. Although this may not seem a proper goof as it was a dream, Mary Alice herself says that it was the last time she saw Lynette and that she shot herself "moments later".
When Gabrielle shows up at Lynette's front door in the flashback, Lynette has a picket fence even though it was built several years into the show.
During Lynette's flashback where she forgets Penny in the car, the tree house in her garden can be seen even though it wasn't added until much later.
Although most of Mary Alice's house was re-painted to its original color for the flashback sequence, the side nearest Bree's house remains green from its new look in season five.
The interior of Lynette's house is painted blue in the flashbacks, but during the time the flashbacks would have taken place, the interior of her house was light pink.