"A dog and pony show" means a display or presentation that is extremely elaborate. The phrase typically refers to advertising or sales material and has a closely related phrase, "dog and pony act," which refers to a similarly elaborate presentation that is more active and in person.
The phrase comes from the 1920s when actual dog and pony shows often accompanied circus acts. In some cases, these shows were intended to hide illicit liquor sales at an event. Since this time, the phrase has picked up negative connotations. In many cases, it is used sarcastically to describe poor performances or displays.