I have no idea if anyone on here has done this, but the FTC frowns heavily on forging customer testimonials.
I think they can only enforce these laws when it is in mail or online form. So I guess fliers may be out of that realm, I still would not advise it.
I just read about some companies getting popped. The FTC may not be looking into any of our companies, but rumor is that some of the companies getting caught were turned in by their competitors. They do pay attention.
Just something weird I have never thought about…