There are some easter eggs and secrets in Scarface - The World Is Yours, here is a list:
Gilligan's Island[]
There is an Island in The Islands which is a reference to the 60's TV Sitcom Gilligan's Island. The Island is unmarked on the map, therefore it's a bit difficult to find it. The island has a wrecked vessel, a bar and some people similar to Gilligan's Island characters.
Shaft[]
The Oakley Drive-In is a reference to the movie Shaft, as the word "Oakley" refers to the Oakley actor Richard Roundtree who played as Shaft. In addition, Richard portrayed the Oakley Drive-In Owner as well. If you shoot the Oakley Drive-In's sign and destroy it, the word "Drama" will turn into "Shaft".
Brazilian Attendant[]
The player can see a Brazilian attendant at Pedro's Pawn Shop. If Tony talks to him, he will say quotes like "Puta que pariu,essa porra é falsa!" which is translated to "Holy Fucking shit, this shit is fake!". He is voiced by the Brazilian actor Rodrigo Santoro.
Dumpsters[]
Tony can go near the green dumpsters in Miami and The Islands. If he has a low health level, pressing the "enter vehicle" button will make Tony urinate and gain a small amount of health.
Shark[]
If Tony swims far away from an area, a Shark will eventually appear and eat Tony. Tony will do the Wilhelm scream and the screen will then black out.
Girl eaten by a Shark[]
On a pier at South Beach, if Tony goes to the edge of the pier, you will see a girl swimming with a Shark following her, the Shark will eat her off-screen.
UFO[]
Near Lobster Cay, there is a sunken UFO in the sea.