Even though Hugh's right hand is severely injured by a fan while staying at Hill House, there is no visible scar on Adult Hugh's hand.
Throughout the series, the cook stove/range in Hill House is an electric model from the 1940s or '50s, clearly (and wrongly) shown with an exhaust duct extending from behind it and into the wall. Electric ovens don't need exhaust ducts - gas ovens vent the byproducts of combustion. The model in the episode isn't dual fuel. There's no need for this duct at all.