Okla. Stat. tit. 15 § 63 : Contracts — Nature of Contracts —Consent, Duress, Fraud, Mistake, Acceptance, Revocation, Ratification — Mistake of Fact TEXT PDF Mistake of fact is a mistake not caused by the neglect of a legal duty on the part of the person making the mistake, and consisting in: 1. An unconscious ignorance or forgetfulness of a fact past or present, material to the contract; or, 2. Belief in the present existence of a thing material to the contract, which does not exist, or in the past existence of such a thing, which has not existed. Okla. Stat. tit. 15, § 63 R.L. 1910, § 908.