Searching for a quick, effective way to evoke the warlust-driven future world of Starship Troopers, director Paul Verhoven created a series of fake TV spots that characters watch in the movie. You can see one this clip, a patriotic ad for the Mobile Infantry which captures both the weirdness of a future where humans fight bugs, and the familiarity of a culture where TV commercials are still bizarrely perky and strained. Other scifi creators have also gone the Verhoven route, adding realism to their alternate realities by peppering them with ads. See some of the creepiest and best of the bunch below.
One of the most infamous fake commercials from a scifi movie is this ad for Fruity Oaty Bars, a made-up product that appears in Firefly spinoff flick Serenity. Director Joss Whedon wanted to evoke the Asian-Western mashup culture of the far future in this ad, which looks like a mixture of Indian, Chinese, Japanese, and North American iconography. In the film, it also contains a subliminal message that sets off government experiment River's "kill kill kill" programming — when this perky clip airs in a bar, she goes apeshit and murders everyone in the joint.
For sheer audacity in world-building, one of my favorites of the bunch is this ad, from Confederate States of America, for the Slave Shopping Network. The flick takes place in an alternate future where the Confederacy won the Civil War, and now slaves are sold on HSN-esque channels, and given Prozac to make them better workers. I just love the way the nice white lady says "You can have the whole family or break them up!" Creeptastic.
Then there are movies that simply update today's brands for tomorrow, to give you a sense of how familiar products might evolve. You may have noticed in 2001: A Space Odyssey that this happens quite a bit. There are references to the Hilton and Howard Johnsons hotel chains, Crest toothpaste, and these two shots showing that IBM will be making spacesuit and spaceship controls in the "far future" of 2001.
You can see more product placement from 2001 here.
Meanwhile, Pepsi actually worked with the Back to the Future creators to imagine a future branding strategy for Pepsi, including a product called "Pepsi Perfect." You can buy Pepsi Perfect bottles on eBay for way too much money.