After Steve destroyed Carl's clipper ship, his suit of armor looks new. But when he returns a moment later, there is a big dent in the front of his suit. Also, in earlier scenes, it looks like the dent was repaired from the inside, as though Steve removed the costume, hammered it out, and put the suit back on.
Sleep-walking is one thing: Sleep-putting-a-ladder-against-the-side-of-the-house-and-climbing-through-the-window, as Steve does on the second night, is not possible. Also,as he is about to leave the bedroom on the second night, you can tell his eyes are not fully closed.
In Urkel's flashback, he seems to clearly recall conversations and events that happened in the minutes before he entered the house, despite the fact that he was not there yet.
When Steve is performing the lie detector test on Carl, Carl says he is 38 years old. It is previously revealed that the Winslows had Eddie when they were 18 years old and Laura at 20 years old. If he was, in fact, 38, Laura would be 18 and Eddie would be 20 in this episode; which was not the case.
When Steve falls off the donkey, the shadow of a boom mic can be seen on Laura's head.