When Gaal is walking through the dessert with Hari Seldon, Hari's steps don't leave footprints as it's supposed to be a hologram. That's a subtle detail that shows great attention to detail
The story with Poly Verisof and Brother Constant going to Korell to rescue trader Hober Mallow is a somewhat loose adaptation of "The Traders" (the fourth story of the first Foundation book), but all the characters and settings are changed. The novella is entirely comprised of new characters: it's about trader Limmar Ponyets going to Askone to rescue Master Trader Esker Gorov.
The planet Korell is from the book; in the novella "The Merchant Princes" (the fifth and last one from the first book), trader Hober Mallow goes to Korell to investigate after Foundation ships go missing.
The character of Hober Mallow finally appears in this episode. However, he is wildly different from the book version: here, he is a young and goofy smuggler, frequently used as comic relief (not unlike Peter Quill in Guardians of the Galaxy (2014)), while in the books, he is a hardened trader-turned-politician who is always very serious.