As Mr. Priest is closing in on Dirk and Todd he calls out for Svlad Cjelli several times. According to the original book by Douglas Adams (and Season One), Svlad Cjelli is Dirk's actual name and Dirk Gently is his pseudonym.
Among the items at the "slumber party" at the Sheriff's station is an improvised bong made from a traffic cone and clear plastic tubing.
Suzie's sweatshirts have shown her progression with the wand. She wore the first one, "Don't make me use my SUPERPOWERS," when she first uses the wand. The second, "I can't believe it", was worn while she discovers the wand's powers. The third, "If your eyes hurt, it's because you are looking at a star", was when she fully accepts what she can do with the wand. The fourth one, "Girl power", is when the wand's power is driving her ambitions.
Bart previously made a remark in Very Erectus (2016) that if she ends up in a cell, it will be because, "Maybe that's where Dirk Gently is." In fact she does end up in a cell with Dirk.
One of the concert goers entered The Sound of Nothing wearing a fluffy pink fur coat. Dirk wakes up wearing this coat.