Are there any currently released cards that actually apply the golden rule (where card text overrides game rules)?

Ruling: Yes, several cards apply the golden rule where card text overrides game rules. Examples include Brynhir (prevents opponents from playing cards despite normal timing rules allowing it), Mageseeker Warden (similar restriction), Magma Wurm (changes how units enter), and Zhonyas (overrides game rules).

Nuances:

• Tideturner is debatable as an example because its interaction with hidden card targeting restrictions is explicitly covered in the rulebook with the clause "unless the ability explicitly restricts targeting in a way that makes this impossible"
• The hidden card targeting rule states targets must be chosen from the same battlefield unless the ability explicitly restricts targeting in a way that makes this impossible, which covers Tideturner without needing the golden rule