If you put a color cube on an Octopus Queue, the attribute of Queue (object?) changes from null color to yellow or red. Is this how real programming works? Perhaps there should be a visual signal showing that the attribute of the Octopus Queue has changed--a yellow/red top hat?

Comparing a color of a place (queue, input, output, etc.) will end in a result of comparing with a cube that can be taken out next. This is called 'Peek' in real programming.
We will add some visual improvements to that.

I have noticed that putting a color cube changes color attribute, overriding previous color. Thus if I put red after yellow the Output will be yellow until I put another color cube on it. It's not visually obvious what current color the Output is.

Yeah Output works in a reverse way, the recentmost cube will be used when comparing colors for Output.
We will make it clear how it works.