allusion / illusion
An indirect reference versus a false appearance.
An allusion is an indirect reference, usually to a text, event, or person: an allusion to Job. An illusion is a misleading appearance or a false belief: an optical illusion, the illusion of control. You make an allusion to something. You have an illusion of something, or you are under an illusion.
Examples
Use The stopped clock in the mural is an allusion to the mill fire.
Use Mirrored panels behind the bar create the illusion of a second room.
Avoid The stopped clock in the mural is an illusion to the mill fire. (Illusion is the error: an illusion is a false appearance, and the clock refers to the fire. Write allusion.)