The laser tag place that Saul tries to get Walter to use as a money laundering business in Abiquiu (2010) - Hinkle Lazer Base - is one of the job advertisements in the newspaper that Jimmy is reading through in the beginning.
The plaster cast that Kim wears on her right arm was no prop but an authentic cast applied each morning by paramedics. At the end of each day's shoot it had to be removed with a special saw. Rhea has said that it helped her flesh out her character a little better because of being unable to remove the cast between takes.
The Albuquerque Isotopes are a real minor leagues team; however, the name is based on a fake one. In The Simpsons (1989), the Isotopes were Springfield's local team and property of Duff Breweries, who was going to move the team to Albuquerque much to the town's dismay. The year after the episode came out the city voted to make the Isotopes their new team's new name.
Jimmy (in his Gene persona) is unnerved by the Omaha cab driver's Albuquerque Isotopes air freshener. Later in the episode, Mike watches an Isotopes game on TV. In real life, the Isotopes are a minor league baseball team and the AAA affiliate of the MLB's Colorado Rockies. Exactly two years prior to "Smoke"'s original airing, the team hosted "Better Call Saul Night" at Isotopes Park. Bob Odenkirk threw out the ceremonial first pitch, and the team wore special jerseys bearing Jimmy's face.
The piece playing at Chuck's funeral, "Sicilienne," is what he was playing on his piano in a previous episode. In this episode it has an added violin accompaniment, which was the instrument Chuck's ex-wife, Rebecca, played.