When Sally is getting ready to shoot her scene on the soundstage she is told that the production is in "meal penalty". A meal penalty is a financial penalty producers incur for eating into their workers' meal time. In California, workers are protected under the California Meal Break and Rest Law, guaranteeing them rates of pay depending on how much meal time is taken away.
According to Bill Hader, the one-take shot of Sally walking through the soundstage and onto set was the very first thing shot for season 3. They shot it 16 times, and the 16th take was used.
While checking messages on his laptop, Barry is listening to "The Unforgiven" by Metallica.