Some more modern ice-cooled reefers received rolling plug doors, as shown below, but most were the two-part hinged type - this was to accommodate the thick insulation needed to maintain temperatures inside the car.
In addition to the insulated doors, sides and roofs, reefers were usually fitted with end bunkers for the ice - some had fold-down interior shelves inside the bunkers, which offered "stage" icing, used where a less than full bunker-load of ice was required. Usually, there were drains at all four corners of the car's underbody, to allow for disposal of the melt water. Many cars were fitted with floor racks and fans, to allow cold air to be circulated under the lading, as well as around and over it.
In the photo below, the drains can be seen above the outboard wheel of each truck.
The car below shows the fan housing and drive belt cover near the inboard end of the left truck: the box below the car's side is for the drive belt, while the fan housing is the circular object on the car's side.
Reefers in dressed meat service had meat-hook tracks fastened to the underside of the car's roof - a swing-out extension at the packing plant was use to connect the plant's track system to that of the car, allowing for easy loading/unloading.
Wayne