In his review of The Room, after the point in the movie where Johnny kills himself and Lisa asks if he's dead, he quotes Monty Python's "Dead Parrot" sketch to answer the question.
In the Mighty Morphin' Power Rangers movie, the Critic's impersonates Adam about "Going into anime", which is quite true in that Johnny Yong Bosch (Adam's actor) went on to become one of the most well-known anime voice actors today.
In his Red Sonja review, the Critic references Brigitte Nielson's relationship with Flavor Flav a few times... Even though she ended up marrying someone else.
Whenever actor Tim Curry is featured in any show/movie that the Nostalgia Critic reviews, it's often accompanied by either a picture/video of Dr. Frank N Furter and/or the song Sweet Transvestite playing.
In his review of Ernest Scared Stupid, he made a reference to Trogdor.
In his "Inspector Gadget", when making a gag about what the Gadgetmobile would sound like if voiced by Chris Tucker, the Gadgetmobile got pissed about Gadget touching his radio.
A Shout-Out to Star Trek: Enterprise in the review of Ferngully: When Crysta and Zak put their hands together and a sphere of light forms around said hands, the Nostalgia Critic and Chick do the same—and then the Chick says "Now you're pregnant."
His Catch Phrase, "Why top eleven? Because I like to go one step beyond," is a reference to a similar catch phrase on the now forgotten TV show One Step Beyond.
Nostalgia Critic: *smiling* Oh yes! I remember that magic element that was mean to bring back the evil that was almost destroyed... in fact, I was there. (background music starts to play; serious expression) I was there when the strength of men fell.
Nostalgia Critic: Throw it into the fire!
*Mario stares quietly with the element in his hands, thinking*
Nostalgia Critic: *desperate* Destroy it!
Mario: *calmly* A-no. Suck my big fat meatballs. *Mario runs away*
In his first video reviewing Nostalgic Commercials, he ends the video by singing Poor Jack of all things! And the lyrics are almost entirely preserved, save for necessary changes. Heck, ZERO even shows up to give the Critic a Santa Claus hat! It came out of nowhere, but it blew me away.
During the Mr.Magoo review, he labels one ambiguously ethnic character "the Kwisatz Haderach of stereotypes, offending all at once".
The Scooby-Doo review had many parallels to the series finale of Star Trek: The Next Generation: there is a convergence of past, present, and future which ends up threatening all of humanity; Roger says the line "All good things must come to an end" just as Q did; and it ends with the Critic joining a poker game and realizing he should have done so long ago.
In the Pearl Harbor review, Michael Bay takes all the copies of his film in a bag and drags it up a flight of stairs with great difficulty, somewhat reminiscent of the famous scene in The Mission when Rodrigo Mendoza trudges through the jungle and then climbs up a waterfall while dragging a net containing his armor and weapons as penance for killing his brother.
Nostalgia Critic: And you know what, Mr. Speilberg? Before you even knew what you had, you packed it, you packaged it, you slapped it on a plastic lunchbox, and now [bangs table] you're selling it, [bangs table] you're selling it!
During the editorial "Why is Loki So Hot?" he pulls up this very wiki's The Woobie trope page in-universe clearly trying to hide the fact that he doesn't know what the term means, and is dismayed to see that he's on there himself.
During his A.I. review, he refers to David's potential death as being sent to silicon heaven.