This is the loaf of bread and 'lightsaber' laser knife that Trillian uses to show Arthur how it will make toast as it cuts the bread in the kitchen of the Heart of Gold sapceship. The bread is a foam-latex prop with one loose slice (there's another slice somewhere). The knife holder can hold four knife handles and has a little red LED on it. The knife handle I have is the hero light-up one. There's a small transluscent piece of plastic sticking out of the handle that lights up bright orange when a button is pressed.

 
Here you can see the handle the orange part lit up:

Here's some screen shots of these props being used: