The picture is apparently loosely based on actual real-life events regarding the sinking in 1968 of the Russian submarine the K-129. The Wikipedia website states: "K-129 was a Project 629A (NATO reporting name Golf-II) diesel-electric powered submarine of the Soviet Pacific Fleet, one of six Project 629 strategic ballistic missile submarines attached to the 15th Submarine Squadron based at Rybachiy Naval Base, Kamchatka, commanded by Rear Admiral Rudolf A. Golosow. In January 1968, the 15th Submarine Squadron was part of the 29th Ballistic Missile Division at Rybachiy, commanded by Admiral Viktor A. Dygalo. K-129's commander was Captain First Rank V.I. Kobzar. K-129 carried hull number 722 on her final deployment during which she sank on 8 March 1968. It was one of four mysterious submarine disappearances in 1968; the others being the Israeli submarine INS Dakar, the French submarine Minerve (S647) and the US submarine USS Scorpion (SSN-589). The Soviet Navy deployed a huge flotilla of ships to search for her but never found her wreck. The United States attempted to recover the boat in 1974 in a secret Cold War-era effort named Project Azorian. The vessel's position 4.8 kilometres (3.0 mi) below the surface was the greatest depth from which an attempt had been made to raise a ship. The cover story used was that the salvage vessel was engaged in commercial manganese nodule mining."
Website Box Office Flops, which is "A Database Of Films That Failed At The Box Office", says of this movie: "RCR Media financed Phantom (2013) for $18 million and K5 Intl. sold foreign territories, which wasn't more than a handful of them. The submarine thriller staring Ed Harris and David Duchovny grossed just over $100k outside of the US. RCR originally tapped Sony to distribute the pic's domestic release, but RCR Media ended up self distributing Phantom (2013) in the US and went big with a 1,118 screen release - which opened to a disastrous $508,000, posting one of the worst per screen averages of all time at $454 for the weekend - placing far outside the top 10 at #23. Phantom (2013)'s theater count was reduced to 407 in its second weekend and posted an 88% decline in its second weekend with a $61,050 weekend and ended its run after just three weeks with $1,034,589. Self distributing would see RCR receive a small percentage of the gross from theater chains (Regal Cinema pays out only 34% to independent labels) and they would see back about $400k, which would barely put a dent in the modest marketing spend. Phantom (2013) went straight to video in most major markets, including the UK, Germany, Italy and Australia."
The name of the film's theme song / music-video tie-in for this movie is called "An Ocean Away". It is sung by Rachel Fannan and was composed by Fannan and the movie's composer Jeff Rona. The track was mixed and produced Carmen Rizzo. The video was directed by Adam Bluming. "An Ocean Away" is included on the movie's soundtrack published by Milan Records.
This film's opening prologue, which is a quotation, reads: "If the Cuban Missile Crisis put the United States and Soviet Union within yards of nuclear war . . . . . . then the sudden disappearance of a Soviet ballistic missile submarine in May of 1968 brought the world within inches" - Kenneth Sewell - Cold War historian, author [See: Kenneth R. Sewell].
The trivia item below may give away important plot points.
The film's closing epilogue reads: "At the peak of the Cold War, a Soviet ballistic missile submarine went missing in the South Pacific. Decades after she was raised, her true intentions remain classified by both the United States and the Russian governments. It is believed her missile was later recovered by the Americans, unexploded, from the ocean floor."