Luke scans a barcode that is on a sticker attached to the power supply unit of a PC and gets information about the processor. A sticker on a PSU shows you information about the energy levels it provides. The information about the computer components would, if at all, simply be listed on a sticker attached to the back of the case.
When everyone is stuck inside the panic room / bunker, it's stated that there's no cellular service. Yet a cell phone is used to scan a barcode and look up what it is, and also to retrieve voicemail - both of which require cell phone service.
When they are all trapped in the safe room, Aldon uses the computer. No keyboard, mouse, or display are attached. Only the power cable.
Aldon eats a can of fruit cocktail in the Soviet Era bunker with a pop top. These weren't available in the USSR in the 1980's.