The hovercraft are depicted as large passenger vehicles, with pressurised, spacious and comfortable interiors for the crew and passengers. They have an elegantly rounded, but thick and robust body (the cockpit small in comparison), with the fuselage seamlessly transitioning into the wings. The wings go from fairly stubby to an abruptly thinner and curved shape as they spread outward. Their tips descend into a downward-pointing control surface. The front ends of the fuselage house large air intakes for the propulsion engines. The exterior surface of a hovercraft has a silvery, metallic shine.
During flight, the vehicles hover at a relatively small height above the surface of the surrounding terrain. They fly at very high speeds, though are only subsonic. They also seem to be capable of vertical take offs and landings, instead of conventional landings on runways. When arriving at the Delos hub, they utilise tall concrete platforms (in the shape of a flat-topped pillar) for vertical landings.
Real world comparison
The hovercraft depicted in the film are not the usual, sea-bound or land-bound version, utilising a cushioned base for gliding on surfaces. Instead, they are far closer to Ground effect vehicles, an experimental subset/hybrid of aircraft and speedboats. During flight, GE vehicles hover over a particular surface (usually sea, potentially also dry land), but only at a limited height. They do not make contact with a surface during travel, but they also can't fly freely in the manner of an aircraft. In a sense, they fit the "hovercraft" description even more literally than the conventional, cushioned hovercraft.
During the 1960s and 1970s, both major sides of the Cold War experimented extensively with GEV development, for military and civilian applications. The Soviet Union famously founded a whole ekranoplan industry for sea-going GEVs, with vehicle development centres in the area of the Caspian Sea. The Soviet ekranoplans belong to some of the largest GEVs constructed to date (as most types are closer in size to floatplanes and motorboats).
The original Westworld was filmed in the early 1970s, at a time when news about GEV experimentation would have commonly appeared in tech-oriented magazines and publications. This might have inspired the production designers to depict such an unusual vehicle, in keeping with the film's effort to present a plausibly futuristic world set a decade or two in the future.
Due to their vertical take off and landing capabilities, the film's hovercraft seem to have some features in common with VTOL aircraft.
The closest contemporary equivalent to the film's passenger hovercraft are the WSH series of passenger ekranoplans for regional transport, developed by the South Korean company Wingship Technology. Though they are non-jet-powered and reliant on hovering above sea surfaces, the largest prototype can transport up to 50 people in one flight.
Behind the scenes
The exterior shots of the hovercraft, such as those of the flight low above the desert terrain amd the landing sequence, were depicted with scale miniature models. The interiors, including the cockpit and the passenger area, were studio sets. Rear projection of flight footage at a low altitude was applied to the interior sets' windows, depicting the surrounding arid, desert landscape passing by at great speed.
Information on the scale model for the hovercraft is currently scarce, including who its original designers and builders were. As of 2013, one of the surviving models of the hovercraft could be seen displayed (along with other models) at a workshop of the Scale Model Company, headed by Isao Hirai.