Nadia: The Secret of Blue Water (NES)

Music (Brahms/Faure): Two of the songs in this game are real music: one song borrows from "Hungarian Dance No. 5" by Johannes Brahms, and another borrows from "Sicilienne (from Pelleas et Melisande)" by Gabriel Faure. (Credit: Terry Trojan)
Status: Unverified

Namco Museum Vol. 1 (PS1)

Cross-Series (Ridge Racer): The "Namco Wall" in the Pole Position room is from Ridge Racer. (Credit: Michael Morissette)
Status: Unverified

Character Cameo: Ms. Pac Man is in the opening movie. (Credit: Michael Morissette)
Status: Unverified: FO's Note: This one I'll count since Pac-Man is included on this compilation, but not Ms. Pac-Man, and she's not in the original Pac-Man. But be careful on character cameo submissions with compilation games.

NBA Jam (Multiplatform)

Famous Person (Bill Clinton/Al Gore): There's a code to play as President Bill Clinton and Vice President Al Gore.
Status: TRUE: Verified by FO.

Famous Person/Cross-Series (Various): NBA Jam contains Raiden and Scorpion from Mortal Kombat, and TONS of rap/funk stars such as George Clinton, the Beastie Boys, Jazzy Jeff and the Fresh Prince, etc., as hidden playable characters. (Credit: Yashiro Nanakase)
Status: TRUE: Verified by FO.

NES Open Tournament Golf (NES)

Character Cameo: Essentially a Mario game anyway, but worth noting that Donkey Kong takes care of the prize money in the Club House. (Credit: Mark Kelly)
Status: TRUE: (Screenshot) proves it.

Neverhood, The (PC)

Music (Revolution #9): There's a track in the OST called "Resolution Number 8" which is a reference to the Beatles song "Revolution #9". In fact, the whole song (if you can call it that) is a parody of the Beatles track. It's a series of non-sequential sounds and instrument loops layered over a man repeating "Number 8 Number 8 Number 8 Number 8" over and over again. The Beatles track was pretty much the same only the man repeated "Number 9", not "Number 8". (Credit: Andy Thorley)
Status: Unverified

Nightshade (NES)

Famous Person (Bruce Lee): The Ninja Mistress mentions Bruce Lee in her battle introduction. (Credit: Codie Martin)
Status: TRUE: (Screenshot) proves it.

Literature (Don Giovanni): If you examine that statue between the two Anubis Statues in the Gallery, Nightshade says it looks like a prop from Don Giovanni. (Credit: Codie Martin)
Status: TRUE: (Screenshot) proves it.

Movie (Goldfinger): The regular gentlemen enemies throw their hats like Odd Job from the James Bond movie, Goldfinger. (Credit: Codie Martin & Will B)
Status: TRUE: (Screenshot) proves it.

Literature (David and Goliath): The name of the Bouncer Boss is Goliath. Of course, this is a reference to the giant from the Bible. (Credit: Codie Martin)
Status: TRUE: (Screenshot) proves it.

TV Shows (Get Smart): When you use the phone booth and your popularity's in the blue zone, an elevator in the booth lowers Nightshade into Vortex's hideout, probably a Get Smart reference. (Credit: Codie Martin)
Status: Unverified

Nights into Dreams (Saturn)

Cross-Series (Sonic the Hedgehog): The default names in the high score table are Sonic, Knuckles, Miles, Amy, and Eggman, a reference to the Sonic series. (Credit: Andy Thorley)
Status: Unverified

Ninja Gaiden (NES/SNES)

Programmers: If you look very carefully at the wall in Bomberhead's room, you can see the word "TECMO", the developers of the game, written across the top and bottom of it. They didn't do such a good job on the "M", but the "T", "E", "C", and "O" are very clear. This is easiest to see on the SNES version that's included with Ninja Gaiden Trilogy, and I have a screenshot of this with one of the "TECMO"'s circled in red: (Screenshot)
Status: TRUE: Screenshot proves it.

Movie (Alien): You may have seen this on the "Switched at Birth: Aliens" article, but the demon statues look very much like H.R. Giger's Alien.
Status: TRUE: (Screenshot) proves it.

Ninja Gaiden 2: The Dark Sword of Chaos (NES/SNES)

Character Cameos: The bosses of the original Ninja Gaiden, the Malice Four, all make cameos as regular enemies in Ninja Gaiden 2. Barbarian, the first boss who is a hunchbacked ninja carrying a large sword, is first seen in Level 1 pacing back and forth on various platforms. The other three all make their first appearances in Level 3, the inside of the Tower of Lahja. Bomberhead is the guy who stands on top of pillars and hurls a whirling blade at you. Basaquer is the one that runs onto the screen from the right, then leaps over you and rains down a bunch of daggers. Bloody Malth is the horned guy that shoots a fireball at you that, if you jump over it, returns to him like a boomerang. In fact, the only boss of Ninja Gaiden who does not appear in this game in some form at all is the Masked Devil.
Status: TRUE: Verified by FO.

Movie (Aliens): I mentioned this in the Switched at Birth: Aliens article, but the scene where Ryu meets Jaquio looks a lot like the scene in Aliens where Ripley meets the Alien Queen. With the way Jaquio's head is looking down and those spiderleg-like adornments on his robe stick out to the sides, he even resembles the Alien Queen. This could be coincidence, but consider the Alien-like Statues in Ninja Gaiden and the Chestburster in Ninja Gaiden 3, and the connection seems all the more likely.
Status: Bizarre Coincidence?: But for comparison, here is a (Screenshot) from Ninja Gaiden 2 and a (Screen Capture) of the scene from Aliens in question.

Movie (The Terminator): Robert is so obviously modeled after Arnold Schwarzenegger in The Terminator.
Status: TRUE: Unlike the above scenario, I don't even think this one's debatable. They're wearing the same exact clothes! See Oddities 29 for picture comparison.

Art (The Scream): The image in the background of the Jaquio fight is based on Edvard Munch's "The Scream".
Status: TRUE: Pictures prove it: (Ninja Gaiden 2 Screenshot) (The Scream)

Ninja Gaiden 3: The Ancient Ship of Doom (NES/SNES)

Movie (Alien): When you beat Clancy's first form, a creature that looks exactly like an Alien Chestburster pops out of the wall.
Status: TRUE: (Screenshot) proves it. Note: This looks even more like a Chestburster on the SNES Trilogy version, due to the added color, but I don't have a screenshot of that one.

Ninja Warriors, The (SNES)

Movie (The Terminator): The cyborg skeletons of the Ninja Warriors were obviously modeled after the Terminator.
Status: TRUE: (Screenshot) proves it. Too similar to be coincidence.

Norse by Norsewest: The Return of the Lost Vikings/The Lost Vikings 2 (Multiplatform)

Movie (North by Northwest): The title of the Playstation version of the game is a reference to the Alfred Hitchcock movie, North by Northwest. (Credit: Codie Martin)
Status: TRUE: Verified by FO.

Movie (Star Wars): At the end of the second stage, one of the vikings asks the witch, "Do we have to do this every time?" The witch replies, "Teleporting people isn't like dusting crops, boy", which is a take on Han Solo's "Space flight isn't like dusting crops, boy." (Credit: Codie Martin)
Status: Unverified

Movie (Back to the Future): When you find the time machine, it says one of the required pieces is the "Flush Capacitor", which is a take on the "Flux Capacitor" from Back to the Future. (Credit: Codie Martin)
Status: Unverified

Movie (Star Wars: The Empire Strikes Back): The line "We don't need their scum" is from Star Wars: The Empire Strikes Back in the scene where one of Darth Vader's men comments on the Bounty Hunters he's hired to find Luke and his friends. (Credit: Codie Martin)
Status: Unverified