The title of this episode, "Ghost Light," refers to a theatrical tradition that calls for a single bulb to remain lit on a stage even when the rest of the theater is literally (and figuratively) dark. The origins of this tradition are unknown; it may have emerged from basic safety concerns, but since theater has numerous superstitions, many of obscure origins, it may be only or primarily a symbol for luck. Some members of the general public were first introduced to this tradition when theaters worldwide were forced to close during the COVID-19 pandemic and there were several articles published and news pieces produced about theaters keeping or reinstating the ghost light tradition until performances could resume; for example, a CBS news piece about the Broadway shutdown was titled "Ghost Light: The Year Broadway Went Dark."
Charles says that he saved President McKinley from his "second assassination attempt." William McKinley, 25th US President, was assassinated in Buffalo, New York in 1901. He was the third president to be killed while in office, and shortly after his assassination, his successor, Theodore Roosevelt, signed the executive order rededicating the Secret Service to the protection of the president and other high-ranking government officials.
After getting out of the prop closet, Charles asks if SNL is still on. Steve Martin is a frequent guest host of SNL, and is a member (along with Tina Fey) of the "Five-Timers' Club."
'Sing out, Louise' is a quote from the musical Gypsy.
The supposed ghost is played by Quentin Collins, which coincidentally is one of the main characters on the iconic horror series "Dark Shadows."