Minn. Stat. § 507.33
Where an instrument affecting the title to real property in this state recites the existence of a mortgage against the real property, or some part thereof, where the instrument containing such recital either was recorded prior to 1900 in the office of the county recorder of the county where the real property, or some part thereof, is situated, or was filed prior to that date in a judicial proceeding affecting the real property, or some part thereof, in the district court or probate court of such county, and where the time of the maturity of the whole of the debt secured by the mortgage is not clearly stated in the recital, then such recital may be disregarded and shall not constitute notice of the mortgage, either actual or constructive, to any subsequent purchaser or encumbrancer of the real property, or any part thereof.
Minn. Stat. § 507.33
(8225-1) 1939 c 390 s 1; 1976 c 181 s 2