Of all the obsolete search engines mentioned by Sheldon and Bert, only Infoseek and AltaVista were actually defunct at the time. MSN Search and Ask Jeeves have been renamed Bing and Ask.com respectively, Webcrawler was still active but powered by Google and Bing, and HotBot still existed on its own.
Sheldon states that deep sea divers holding their breath under water have a higher occurrence of a protein that indicates brain damage. Deep sea divers, however, don't hold their breath under water, as this is extremely dangerous and can be fatal. He possibly meant free divers.