One of the internet comments about Stuart's store mentions that the owner never blinked during an entire conversation. During the first scene in the store a poster can be seen behind Stuart with the text "Keep Calm and Don't Blink". (The poster is inspired by Doctor Who (2005) and the famous British "Keep Calm" poster.)
In the opening sequence, Sheldon is wearing a shirt with a transliteration matrix for the comics-version of the Kryptonian alphabet.
When the guys are practicing advancing & retreating, both Leonard & Sheldon are retreating incorrectly by moving their front foot first. When retreating the back foot should move first. Raj & Howard are doing the moves correctly.
On one of the TVs at the bar they play a CFL (Canadian Football League) Hamilton Tiger Cats vs Toronto Argonauts game.
The episode title is also likely to be a multiple reference to Leonard, Sheldon, Howard, and Raj sweating while starting the relatively active sport of fencing, and possibly Stuart sweating when Penny, Amy and Bernadette chat with him in the Comic Store, as well as Howard's Fitbit Activity tracker cheating device.