This was the show's 150th episode.
When Leo's test begins, he's transported to Texas and lands on highway 69. When the route was first built, it was only 150 miles long; oddly enough, this episode marked Charmed's 150th episode.
The Shakespeare that Drake quotes is from "Romeo and Juliet." It is fitting, as Cole and Phoebe's relationship ultimately ended in tragedy.
In the dinner Leo says he's remembering "a feeling", when talking about his unknown marriage, when he turns & sees a couple in a booth cuddling while looking at a menu, then turns to a tv behind the counter where an episode of Friends is on screen showing Joey & Rachel kissing.