The failure of the original copyright holder to renew the film's copyright resulted in it falling into public domain, meaning that virtually anyone could duplicate and sell a VHS/DVD copy of the film. Therefore, many of the versions of this film available on the market are either severely (and usually badly) edited and/or of extremely poor quality, having been duped from second- or third-generation (or more) copies of the film.
Submarine Alert is available for free download at the Internet Archive.
Submarine Alert was another in the series of B films churned out by the Pine-Thomas team. The film villain again was Swedish-born Nils Asther who was featured in three war adventures put out by William H. Pine and William C. Thomas.
The budget for Submarine Alert did not allow for more than a few studio back-screen shots and the use of stock footage and miniatures. During the bombing of the submarine, at least three different aircraft types are inexplicably used during the attack.