Tommy Lee refers to the twins as the "Wonder twins" the actual Wonder Twins will make an appearance later in the series.
Clark mentions Pete Ross when he and Chloe are breaking into the Luthorcorp factory. This marks the first mention of the character since his departure at the end of Season 3.
This happens to be the first time where Clark Kent has not used any of his powers.
Though Clark has already lost his abilities six times (including this one), this is the only time that he doesn't have powers throughout an entire episode.
Tommy Lee mentions that Clark's powers are often circulating topic within Belle Reve Sanitarium, considering how many people Clark has put away in there, this is not hard to believe.