These were meant to be part of the game world. The 'Civillian'(sic) marking was put there to distinguish the leftover Patriot from the in-game Patriot that is reserved for military use.

Civillian Patriot: Yet another leftover vehicle from GTA III.

Definitely a leftover since it is based on a early 90's sedan in GTA III.

Kuruma: Leftover vehicle from GTA III.

Dodo: Leftover Cessna-style plane from GTA III.

Train: Leftover transportation system from GTA III.

Replaced with VCPD equivalent of Maverick.

Police Helicopter: Leftover helicopter from GTA III that appeared on an early screenshot.

The formula was vastly improved with new weapons, further customization, and even more big-name voice actors. Grand Theft Auto: Vice City is a prequel to Grand Theft Auto III, taking place in the 1980s.