The voice of the intercom at the Marine Life Institute is, as frequently said in the film Sigourney Weaver. This is her second Pixar role as she also voiced the main computer of the Axiom, the ship in the movie WALL·E (2008), which was also directed by Andrew Stanton.
Along with Fluke and Rudder, there is a third sea lion at the Marine Institute named Gerald. Interestingly enough, Gerald was the name of the pelican that almost swallowed Marlin and Dory in Finding Nemo (2003), only to be stopped by Nigel.
Characters from other Pixar films make cameos as visitors to the Marine Institute. These include the daycare children from Toy Story 3 (2010), some adults and teenagers seen in Inside Out (2015), and some of the dentist's patients (particularly the young boy and mother who had been sitting in the waiting room when Darla arrived) from Finding Nemo (2003).
While guiding Dory through the pipes in the Marine Biology Institute, Bailey uses his sonar to detect something resembling a large threatening fish swimming through the pipe and about to encounter Dory. This scene resembles the one in Alien where Dallas, is guided through the air shafts in the Nostromo by Ripley, played by Sigourney Weaver.
On April 1st, Ed O'Neill, the voice actor of Hank, was featured with Andrew Stanton as part of an April Fool's joke. The joke involved deceiving viewers into believing that Hank was the oldest and most coveted Pixar Easter egg in history, having been camouflaged as different objects. A similar thing happened with the title character of WALL·E (2008) in 2008.
The tags on the sea lions Rudder and Fluke have "A1" and "13" on their tails. "A113" appears in all Pixar movies, as a reference to the Cal Arts room where many of the animators from Pixar Studios attended.
When Nemo and Marlin are in the tidal pool exhibit, they meet a loquacious clam, voiced by the film's Director Andrew Stanton. When they ask the clam how he is doing, he enthusiastically responds, "I'm happy." This is a gag relating to the colloquial expression, "Happy as a clam."
This is the third Pixar sequel where the supporting character from the previous film becomes a main protagonist (i.e., Marlin was the main protagonist of Finding Nemo (2003), but in Finding Dory (2016), Dory is now the main protagonist). The other two films are Monsters University (2013) (where Mike takes on the role as main protagonist from Sulley in Monsters, Inc. (2001)) and Cars 2 (2011) (where Mater takes on the role as main protagonist from Lightning McQueen in Cars (2006)).
The structure of telling Dory's backstory through the small flashbacks was an idea originally conceived for Finding Nemo (2003). Andrew Stanton planned to reveal the loss of Marlin's family through gradual flashbacks that would be triggered by events he experienced in the present, but the idea didn't pan out in execution, particularly for making Marlin initially hard to like or empathize with. The narrative was instead shifted to show Marlin's tragedy at the very beginning, and the flashbacks were scrapped, although Stanton revealed he would like to use the framework in a future film.
Marlin and Nemo narrowly escape an attack from a Giant Squid early in the film. Nemo is named after Jules Verne's literary seafaring hero, Captain Nemo. Captain Nemo is perhaps best remembered for his exploits in Verne's book, Twenty Thousand Leagues Under the Sea, where he narrowly escaped an attack from a Giant Squid in the Caribbean Sea. Nemo and Marlin's battle with the Squid is a clear nod to Nemo's namesake.
First Pixar follow-up film where Pixar legend John Ratzenberger has a different role from the previous. In Finding Nemo (2003), he voices a school of Moonfish who form shapes and help Marlin and Dory get to Sydney, while in Finding Dory (2016), he voices a crab named Bill that Dory and Hank meet at the Marine Institute.
In the Spanish-dubbed version screened in Mexico, the voice of the intercom at the Marine Life Institute is performed by Dr. Rodolfo Neri Vela, a Mexican scientist and astronaut that has worked with NASA.
The water pipe seen overhead in the institutes quarantine room has the same "Seawater Supply TL59" label as the overhead pipe in the loading zone of the "Finding Nemo Submarine Voyage" attraction in Disneyland.
Unlike Finding Nemo (2003), Dory is referred to by her species name in Finding Dory (2016), a Blue Regal Tang. She also never gets Nemo's name wrong with Marlin having to correct her, and refers to Marlin by name for the first time in the film.
The eyebrows on Gerald, the third Sea Lion who has no dialogue, resemble those of Baby Gerald, Maggie Simpson's archenemy from the Fox Animated Sitcom The Simpsons (1989). Many alumni of The Simpsons (1989), most notably Brad Bird, have gone on to work at Pixar.
The film's theme song, "Unforgettable," was made famous as a jazz standard by the late Nat 'King' Cole, and was covered as a posthumous duet with his daughter, the late Natalie Cole. For Finding Dory (2016), it is covered by Sia.
A Barracuda Character voiced by David L. Lander was supposed to appear in the film, but the character was likely scrapped because of it seemed hard to make a Barracuda not be an enemy after the one seen at the start of Finding Nemo (2003).
This is the third Pixar film that follows up to a previous where voice actors are replaced, which goes for Nemo, Sheldon, Tad, Pearl, Squirt and Jacques. The other two are Toy Story 3 (2010), with Andy (though his voice actor from first two films did reprise his role for Andy as a Grown up) and Slinky, and Cars 2 (2011) with Filmore and Red.
Voiced by Ed O'Neill, Hank the Octopus is initially grumpy, misanthropic, and wishes to live alone away from family or friends. O'Neill is no stranger to playing a grumpy character who wishes to avoid his family. One of his most famous roles is the hapless, misanthropic shoe salesman, Al Bundy, on Married with Children (1987).
The trivia items below may give away important plot points.
At the end of the credits, an extra scene reveals what the Tank Gang has been up to, apparently still in their Plastic Bags having floated all the way to the Marine Institute and become a part of it, being covered with algae (except for Jacques's who in Finding Nemo (2003) movie was addicted to cleaning (being that he's a cleaner shrimp)).
Jerome Ranft replaced Joe Ranft for the role of Jacques after his brother's death in 2005. This is the first time where one of Ranft's Characters have been replaced in a later film, as in Toy Story 3 (2010), Wheezy and Lenny only made a Silent Cameo at the start of the film, and in Cars 2 (2011), Red never spoke. It's also only the 2nd Pixar Film to star Jerome Ranft, the first one being Up (2009) 7 years prior.
The Symbol on the steering wheel of the truck that Hank steals and drives into the Pacific Ocean resembles the iconic Luxo Ball, and it's the first time the Luxo Ball's Cameo is not featured as a ball, as well as the first time it has a significant part of the film's plot. Some people may think that the symbol the Luxo Ball symbol on the steering wheel also represents Captain America's shield from the Marvel Universe.