Talking about my dreams generally, including non lucid dreams.

Computers
The interface is often different to what I'm used to. I brush off these peculiarities as just a different OS or a different desktop environment. I can usually manage to get them to accomplish the task I intend. I sometimes find nice web sites and I'm slightly disappointed when I wake up to find my new valuable resource never really existed. Dream GNU/Linux is unfortunately quite susceptible to malware. A recent nightmare (maybe more of an 'anxiety dream') virus replaced my OS interface with something that looked like a 2D 16-bit console game with an animation of pixelly anime monster rape.

Televisions
Nothing to report. I don't watch much of this in real life. But I do play videogames with a TV/monitor. In dreams, playing games = getting seamlessly sucked into them. Haven't tried it in lucid dreams, might be a good teleportation technique.

Light Switches
Unreliable. From a recent false awakening (indeed from a LD): my lamp near my bed failed to switch on the first time. I figured I pressed the wrong switch. Tried another one, then it worked. In real life I have only one damn switch up there.

Mirrors
Haven't done much playing with these. I passed through one once in a lucid dream, just teleported to another part of the house.