Two sailors from 1943, David Herdeg (Michael Pare) and Jim Parker (Bobby Di Cicco), become Fish out of Temporal Water when the US Navy destroyer they are stationed on vanishes as an unforeseen side-effect of an experiment in creating an electromagnetic Invisibility Cloak, and they find themselves in 1984. While they deal with the culture shock, Parker is overcome by the out-of-control side effects and disappears. Herdeg, searching for an explanation for what happened to him, winds up at a military installation where it is revealed that a second cloaking experiment is underway, this time involving an entire city. It, too, vanished, and now there's a huge vortex in the sky that is sucking everything into it and growing larger.
It turns out that the interaction of the two experiments, one in 1943, the other in 1984, has created a time warp that captured both the destroyer and the city and threatens The End of the World as We Know It. Herdeg is given an experimental suit to protect himself from the effects of the vortex, and allows himself to be sucked back in in an attempt to shut down the destroyer's cloaking field.
The movie is Inspired by , and takes its name from, a Conspiracy Theory which itself revolves around a supposed invisibility experiment conducted during WWII, which is said to have resulted in the same side effects as depicted in the movie. The story's most probable origin lies in WWII experiments with whole-ship degaussing as a countermeasure against magnetically triggered sea mines, likely conflated with contemporary generator experiments aboard a destroyer which produced visually impressive, yet almost entirely harmless, corona discharges.
The Philadelphia Experiment provides examples of:
- All Is Well That Ends Well: Despite the fact that Herdeg is indirectly responsible for the burning death of a car full of his subordinates, and the injury of some in the one he was riding in, he's more than happy to be the one driving Herdeg out (and engaging him in idle chit chat "So, what did you think of 1984?") so he can get back to 1943.
- Based on a Great Big Lie: Aside from a complete lack of any evidence supporting the experiment, the USS Eldridge was in the Carribean on a shakedown cruise during the dates specified, and four of the men mentioned by name to have died actually survived the war, one of whom eventually commanded his own ship. Even the creator of the story, a former merchant sailor, admitted to making it up.
- Body Horror: After the ship returns from its trip many of the sailors are severely burned, but several are even seen "phased" halfway through a metal walkway... still living.
- Conflict Ball: The military in 1984 is unnecessarily aggressive in trying to capture Herdeg and Parker, and the latter are unreasonably afraid, when they are both members of the U.S. Navy and, if anything, should expect reasonable treatment from the government. The irrational behavior from both parties creates all the conflict in the second act of the film.
- Covers Always Lie: The cover (seen here) is misleading. The dark thing with the headlights in the center had nothing to do with the actual experiment, Herdeg is actually riding out in it at the end of the movie to fix everything.
- Developing Doomed Characters: There's a long segment at the beginning setting up the fact that Parker is in love (or married already), which takes place at a dance.
- Did Not Get the Girl: Subverted. Herdeg is forced to leave his Love Interest, Allison, behind when he enters the time vortex. It's strongly hinted that he'd eventually have been sucked back just like Parker anyway. But then he jumps off the destroyer before the time vortex collapses, reappearing in 1984 after a Disney Death.
- Disney Death: Herdeg jumps off of the Eldridge into the vortex just before it collapses. The destroyer reappears in 1943, the town reappears in 1984, and everyone's happy (except for the horribly maimed sailors, one imagines), but where's the hero? Cut to Allison walking through the town... and there's Herdeg.
- Driving Stick: Inverted Upon commandeering Allison's car, Herdeg is so dumbfounded by the lack of a clutch pedal that he has to make Allison drive.
- Fish out of Temporal Water: Actually some scenes of this were deleted. The most subtle bit was Parker's reaction to the bill for two breakfasts and coffee — which probably cost several times the dollar amount it would have in 1943, but we just see his reaction to the check, not the price.
- Foreshadowing: Parker's wife in 1984 tells Herdeg that, "You never came back."
- The Future Is Shocking: The culture shock of Parker and Herdeg arriving in 1984 is played up until they start getting chased by the military.
- Gone Horribly Wrong: The cloaking experiment is intended to hide a ship from radar, not make it vanish entirely.
- The Guards Must Be Crazy: One soldier manages to get onto the elevator with Herdeg. There are lots of innocent bystanders there. The guard waits until after a stop when someone is let onto the elevator — the perfect opportunity to get Herdeg away from said bystanders — and waits until the elevator is even more full and the door shut before attempting to restrain Herdeg.
- Human Architecture Horror: Still-living sailors fuses with the deckplates, anyone?!
- Invisibility Cloak: For a navy destroyer and an entire midwestern town. It's actually intended just to hide them from radar, but clearly doesn't work exactly as intended.
- Lemming Cops: Pursuing cars on foot through snow. Chasing a car through a barn, flipping one car and exploding the other after it rolls.
- Mad Libs Thriller Title.
- Mass Teleportation: A U.S. Navy destroyer and an entire town get sucked into the time vortex.
- Our Time Travel Is Different: The wormhole version.
- Product Placement:
- Löwenbräu beer.
- Coke, several times. The most obvious is the man holding the can label-out as they watch the results of the missile-probe.
- Herdeg watches a commercial for the Rainbow 100, which really was a computer for sale in the 1980s.
- The Slow Path: Poor Parker has to live out 41 years of ridicule while his buddy Herzeg gets to gallivant around in 1984. No wonder he's bitter.
- Stock Unsolved Mysteries: The Philadelphia Experiment.
- Tele-Frag: The fate of several soldiers aboard the ship when it accidentally time-travels.
- Time Travel for Fun and Profit: Parker owns a ranch, but he doesn't seem to be any wealthier than he could have been otherwise. However, he didn't see much of the future before being incapacitated, so didn't pick up a lot of information that could be easily exploited. Herdeg, however, makes a joke at the end about the military probably owing him 40 years of back pay.
- Temporal Paradox: Of the ontological sort — if the time vortex is stopped back in 1943, then how does it start in 1984 and cause the events of the movie? This is, perhaps mercifully, left unanswered.
- Time Crash: The time vortex created by the interaction of the two experiments will cause a horrible calamity if not stopped, as the 1984 end seems poised to suck up the entire planet. There's no corresponding vortex in 1943, however.
- Time Travel: Accidental time travel caused by two experiments in electromagnetic cloaking 41 years apart.
- Very Loosely Based on a True Story: There was a project involving degaussing naval ships to allow them to pass through a field of magnetic sea mines. One sailor was electrocuted, which is an occupational hazard of working with the high-kiloampere currents required to cancel an entire ship's magnetic field, but otherwise it was a success. That's about the closest the film gets to reality.
- Walking Techbane: Of the accidental type; absorbing the electrical shock from the destroyer's generator causes Parker (and later Herdeg) to occasionally short out nearby electronics and attract thunderstorms.
- What Happened to the Mouse?: Blink and you'll miss it: after Herdeg turns off the machine in 1943 and as he walks over to talk to Jimmy on the ship, he puts his 1984 gloves in his 1984 helmet and tosses it off to the side. He never retrieves them, leaving them in 1943. The movie's almost over, and there's no time to bring this up. He returns to 1984 without them.
- What Year Is This?: Parker and Herdeg figure out that they're in the future from copious clues, but have to ask for the precise date.
- You Have to Believe Me!: Parker's "insane" story of traveling in time got him put in a mental institution after he was sucked back. When Herdeg looks him up in 1984, he's a bitter old man.