When Chuck is setting a meeting time with Jill, while speaking in a "nerd code", he says to take the latent heat of aquatic fusion in calories per gram, which is 80, and subtract the atomic number of thulium, which is 69. So, the meeting time was 11.
When Chuck and Jill solve the puzzle box in the Opera house, the timer stops at 00:07, a classic trope from James Bond films.
This episode has a couple references to opera. First and most obvious, two scenes take place in the opera house. Also, the famous Looney Tunes episode titled "What's Opera, Doc?" is playing on the background televisions in the Buy More when Chuck asks Morgan to cover for him.