Not sure if anyone else noticed, but when at the auction house for the "Open Sesame" quest in HoS, Gerlt notices a "Goblet of fire"... interesting choice for an Easter Egg. :
Avid Collector - The Witcher 3 Wiki Guide - IGN
Open Sesame!, Witcher 3: Wild Hunt Quest
Update] When you tell Vesemir you ran into his 'bit of strange' at the auction house : r/thewitcher3
Xbox Game Pass March 2021: 'Gears 5,' 'The Medium' Stay, but 'The Witcher 3' and MORE Bid Farewell! | iTech Post
Bidding Adieu to The Witcher 3 – VIRTUAL BASTION
Open Sesam Witcher 3 | Detailed passage of quest
Open Sesame!, Witcher 3: Wild Hunt Quest
Open Sesame! Walkthrough and What to Buy at the Auction | The Witcher 3 |Game8
Avid Collector - The Witcher 3 Wiki Guide - IGN
Open Sesame! Walkthrough and What to Buy at the Auction | The Witcher 3 |Game8
Open Sesame! - part I - The Witcher 3 Wild Hunt Guide & Walkthrough | gamepressure.com