Invisible details such as wiring and electronics do not affect the visual accuracy of the prop as long as the effects those components are responsible for producing are identical to that of the original.
Blinking lights and illuminated buttons appear everywhere from the bridge of the Enterprise to Darth Vader's belt, and attempting to reproduce the exact circuit boards and lamps faithfully is usually impossible or impractical, particularly for older films.
Similarly, mechanical effects and even the choice of materials often boils down to practicality and the purpose of the prop rather than close attention to detail.
A prop designed to be worn with a costume may be constructed differently than one intended solely for display in a sealed case.
Propping draws from many areas of expertise including drafting, carpentry, electronics, metalworking, Computer-aided design and sculpting and mold making.