When the Smith Brothers trademarked their logo for their cough drops, the product label split the word "Trademark" in two, putting the words "Trade" and "Mark" under portraits of the two brothers. As a result, it has always been assumed that the Smith Brothers' names were Trade and Mark. Their names were actually William (Trade) and Andrew (Mark).
In the 90s, TNT would air promo ads for Godzilla movie marathons as part of their Monstervision TV specials. One promo ad would list the names of various foes Godzilla fought. The problem? One of the monsters is listed as "Baragon" in the promo but is actually Gabara.
The "Target Dog" in the See "Spot Save" commercials is not actually named "Spot". Reportedly, the dog's name is "Bullseye". The "spot" is actually a reference to Target Store's logo.
A radio spot for the (American-owned) chain of Japanese cuisine/teppanyaki restaurants, Benihana, features a customer coming in and asking to speak to Mr. Hana. The maître d' explains to him that there is no such person; "Benihana" means "safflower" in the Japanese language, he says. The customer retorts, "Oh, you can't kid me. I'll bet you're Benny Hana."