The normal "Chuck Lorre Productions" card was replaced with a dedication to Carol Ann Susi (Mrs. Wolowitz) who died three days before this episode originally premiered. In reruns, though, the usual Vanity Card is shown.
In an early scene with Sheldon in Leonard's bedroom, a portrait of Leonard and Penny from the The Prom Equivalency (2014) can be seen on his nightstand.
At the hospital Sheldon sits on the right-hand side of the row of seats (from the viewer's point of view) next to Penny. This corresponds to his spot, which he guards so jealously, on his sofa.
In reality Kaley Cuoco did have surgery for a deviated septum, and she announced it on The Ellen DeGeneres Show (2003) and bravely shared photos of her bruised, swollen face.