According to Blu-ray.com and official product listings, the Blu-ray includes:
: An all-new mini-movie featuring Gru’s unusual pet dog. despicable me 3 blu ray best buy
For the best possible picture quality, the 4K version is available for at Best Buy . Despicable Me 3-Movie Collection [Blu-ray/DVD] According to Blu-ray
: Specifically a scene involving the "unicorn watch" with an introduction by Dana Gaier. despicable me 3 blu ray best buy
: Deep dives into the voice cast, including Steve Carell (Gru/Dru) and Kristen Wiig (Lucy).
A box set including the first three films, often found in various configurations at Best Buy . Key Features & Bonus Content