Once Wilson converts his study into a bedroom for House, if you look closely at his nightstand, you can see Lydia's sunglasses that House wore in the episode Broken (2009).
According to the synopsis, the actor who plays Donny (Jon Seda) also plays a cop on Chicago Fire (2012) and Chicago P.D. (2014). His character is the brother of character Matt Casey's girlfriend. Casey is played by Jesse Spencer (Dr. Chase).
House tells Jon Seda's character that he has "Ortoli syndrome," a made-up condition. The name could reference Jon Seda's character in "Oz" - Dino Ortolani.