Continuity mistake: There had never been any signs of the ship being anywhere close to land, but suddenly the boat appears right next to a city when we see the minions flying past the ship. (00:05:15)
Continuity mistake: During the dance fight towards the end of the movie between Gru and Balthazar Brat the guitar/piano/laser thing swaps from a right-handed item to a left-handed one when Gru gets it.
Continuity mistake: When Bratt steals the diamond for the second time he breaks the window on the ceiling and glass starts to fall. Cut to Bratt and the falling glass disappears.
Answer: I'm going to assume you haven't watched the entire movie. There is a scene in the movie when all minions abandon Gru due to Gru not being willing to return to his prior lifestyle of being evil and committing crimes.
Rassdyt