Factual error: A force of Russian Tu-22 Backfire bombers attacks the aircraft carrier USS John C. Stennis (CVN-74) by sneaking in under the ship's radar. This is all well and good except that carriers usually don't use their own radar, they have Airborne Early Warning aircraft (E-2 Hawkeye's) that can see much further and not give away the carrier's position (let alone the F-14s which would be patrolling too) not to mention the fleet of destroyers other ships guarding the carrier. The whole point is, the US Navy practiced and planned for such a "carrier versus Backfire" battle for years. I guess in the interest of furthering the plot Hollywood has to ignore the immense measures the USN takes to protect those multi-billion dollar assets, not to mention the 5000+ sailors that man them.
Factual error: In the scene where the dock worker receives the e-mail stating 'the day has arrived', the e-mail is dated Mon, 19 Nov 2002. However, November 19 2002 was a Tuesday.
Factual error: The Israeli A-bomb was dropped "at the Golan", yet, the landscape where it is found looks like a sandy desert, and as time flies the bomb is completely covered with a sand dune. The Golan has everything but sands or dunes. The terrain over there is magmatic, rocky and mostly black, as the Golan was an active volcanic area. Had a bomb fallen from the sky, it would most likely remain on the ground, smashed.
Factual error: Why is the President's motorcade so small? There were only a few cars there to protect the most powerful man on the face of the Earth. The President ALWAYS travels with over a dozen Secret Service vehicles, to protect him. Even if when he left the Superbowl was an emergency, all of the motorcade would have left with him also, ruling out the possibility that only some of the cars left with him.
Factual error: When the aircraft carrier is attacked by the Russian aircraft, the carrier is sailing alone. This is not normal as carriers always sail in carrier battle groups, with several smaller ships (cruisers, destroyers) to protect them.
Factual error: When the bomb detonates, the shock wave hits the helicopter that Jack Ryan is riding in and rips the tail rotor off the helicopter. Without the tail rotor the helicopter should have immediately started spinning out of control and dropped straight to the ground. Instead the helicopter continues forward, arcing downward towards the ground like a fixed wing aircraft.
Factual error: Dressler is supposed to live in Vienna, Austria. However, in the final scene, when his car explodes, the county-code on the numberplate is not the one from Vienna, nor from any other county in Austria. What is more the letters have the wrong font and the county emblem is missing.
Factual error: After the US President gives the order to launch the missiles, you see a view of a missile preparing for launch. This is followed by scenes of B-2s launching. The missile shown is an older liquid fuelled missile. The US military retired all liquid fuelled missiles from its inventory long before the first B-2 rolled off the assembly line. As such you wouldn't see both in use at the same time.
Factual error: When the F16 are attacking Russian bases one of the US pilots is wearing sunglasses. Combat pilots do not wear sunglasses when piloting their planes - their helmet has a visor with shaded glass to protect their vision from sun flare.
Factual error: The Trident II, submarine launched ICBM is actually identified as the "D5" not "D3" missile.
Factual error: In the cockpit of the Israeli A-4 Skyhawk being flown in 1973, shows a HUD (Head-Up-Displays) in the windscreen. No aircraft in 1973 had HUDs (Head-Up-Displays). HUDs were developed after 1973.
Factual error: As the President's motorcade is supposed to be approaching Ravens stadium in Baltimore via I-395, the motorcade is on the wrong side of I-395 & is actually traveling away from the stadium - it's unquestionably on the ramp portion of I-395 which leads directly to I-95 north.
Factual error: On the way to the football game it appears that they make the football stadium into a dome stadium. Baltimore doesn't have a dome stadium, this is evident a few minutes later when they show a panoromic view of Baltimore and you can see the 2 stadiums side by side as open stadiums. In the movie, Baltimore has a third domed stadium that is a CGI image in only one shot and not shown later.
Answer: The song is the classic "Nessun dorma", composed by Puccini and sung (in this version) by Bruce Sledge.