In the scene of the Illumination Entertainment logo before the film (as well as on June 19, 2016 NBC airing of Despicable Me 2), Bob walks out and hums, and he shouts "illumination" twice with Minionese accent after the logo spawns.
The melody Bob hums is the beginning of "Der Vogelfänger bin ich ja" from Mozart's opera, The Magic Flute.
The letters that spark first are "MINION". Similar thing occurs in the beginning of the film Sing, but it is these letters that goes out.
A poster for the next Illumination Entertainment film, Sing, can be seen on the back of the bus Max and Snowball.
This film was going to be released on February 12, 2016; but was moved foward to July 8, 2016.
Gru and Kyle can be briefly seen in the dog park in Washington Square Park.
Mel dresses like a Minion in the party Leonard holds.
It is the first film to open over $100 million in the United States that is not a sequel nor based on previously published material.
In the apartment filled with cats, the MSNBC Anchorman can be seen on the TV.
The gnome from Mower Minions makes a cameo appearance towards the end, and Tiberius bumps into one that resembles it.
At the scene when Max and Duke are escaping from The Flushed Pets, an animal gang, a turtle starts bouncing around ahead of them knocking animals out of the way with a video game sound effect referencing the turtles that knock out enemies in the Super Mario Bros. video games.
In the telenovela La Pasión de la Pasión the male character Fernando is voiced by Jaime Camil, who currently plays Rogelio, a telenovela star best known for his role in "The Passions of Santos" in the 2014 series Jane the Virgin.
A scene shows a cab driver listening to his radio, which is playing Happy by Pharrell Williams, a notable song from Despicable Me 2.
On Katie's refrigerator there is a minion eye and a banana in the picture below.
The owner of Norman has two Minion figurines near his bed.
When the film was first announced, it was noted as an "Untitled Pets Movie". However, the film's official title was later announced as "The Secret Life of Pets".
There is a woman appears in Brooklyn who is horrified by disguised Snowball and Tattoo. She is also one of the residents in the Apartment Building.
The film is the third Illumination Entertainment film that uses profanity after Hop (which profanely used "cripple" once and used God's name in vain once) and The Lorax (which used the word "damn" once); the word "hell" is mentioned twice during the Nappy Roots song Good Day (which is played during a big party in Pops' apartment). This is one of the reasons for the film's PG rating.
The Secret Life of Pets was originally going to be released in 2015, however, in September 2013, the date was changed to 2016. The release date change was the same day Universal and Illumination changed the release date of Minions, from December 2014 to July 2015, thus pushing The Secret Life of Pets to 2016.