To begin, we close our eyes. We are told to imagine a science fiction-esque film about a phone booth that is really a time machine from a distant future. Now imagine that time machine is used to hop through time on a whim, interfering with history in some way, and making sure the future remains the future and the past the past, all through the use of this time machine. Now imagine all these important historical figureheads show up and jaunt through time with the main character and his companion. Except the phone booth isn't bigger on the inside; in fact, it's kind of small-ish. Wait, we're talking about Doctor Who, right? No, we're talking about what Doctor Who might be if Pauly Shore and Adam Sandler wrote it-- the 1989 classic Bill and Ted's Excellent Adventure, one of the first breakout film roles for Keanu Reeves (and who doesn't love a young Neo?).

The entire film and the use of time travel in the narrative itself rests on the basis of causality and piggybacking from paradox to paradox, opening and closing time loops and oftentimes leaving questions "unanswered" simply due to having them answered earlier in the film (due to the nature of the time travel). The story begins with a monologue by Rufus (George Carlin) that poses and answers many questions without the viewer even realizing:

Now right away, the viewer is both confused and informed (if they are a first time viewer). The character Rufus lets the viewer know the timeline (2688, 700 years in the future compared to 1988) as well as the fact time travel is a thing, why Rufus is using time travel, and that other planets presumably have life (as he describes it, but not what kind of life). But he brings up a few questions to be intentionally confusing. He notes, "So now I have to travel back in time to help them out," meaning he hasn't done it yet. But he notes that "...this place is great. But it almost wasn't," as in history has already been fixed. But how has it been fixed if he hasn't gone back in time to fix it (assuming he was the one that originally set history straight)? He continues, "If I should fail... the basis of our society will be in danger," thereby confirming that the "saving" hasn't been done yet but also that there's a possibility he might fail, thus causing a different future that is, in fact, in danger, but he would only know that if informed of the danger from the future, but then if he fixed it, how would that future happen. And why is George Carlin not swearing in this movie? But alas, he confirms it will all make sense.

The film conveniently and creatively pokes fun itself in many ways, especially when referring to its own paradoxical nature, as well as provides the viewer a foundation for which the understanding of the film will rely. At the beginning of the film, Bill and Ted are arguing about creating their music video for their band Wyld Stallyns, after causing their poorly functioning equipment to start smoking during their shoot:
Bill: "Ted, while I agree that in time our band will be most triumphant, the truth is Wyld Stallyns will never be a super band until we have Eddie Van Halen on guitar."
Ted: "Yes, Bill, but I do not believe we will get Eddie Van Halen until we have a triumphant video.
Bill: "Ted, it's pointless to have a triumphant video before we even have decent instruments.
Ted: "Well how can we have decent instruments if we don't really even know how to play
Bill: "That is why we need Eddie Van Halen."
Ted: "And that is why we need a triumphant video!"

Overall, Bill and Ted's Excellent Adventure provides a classic and, most importantly, humorous take on what time travel can be used for in film. By using concepts of causality, paradox, and time loops, Bill and Ted (the characters) are able to overcome a great many obstacles (both in time and place) in an effort to pass their history report. Many of the elements and use of time travel are explained throughout the film, leaving few questions unanswered. Paradoxes and time loops are created and closed and the reason for their use becomes a part of the narrative itself, often done humorously. The entire movie is otherwise nonsensical and meant only for the sake of humor. Rather than being an entirely social critique, the film instead uses many pop culture references and in-jokes for comedic purpose. However one critique most excellent is presented by the narrative. Rather than using the time machine for nefarious purposes (as it seems they're trying to do), they use it for actual educational value, not only traveling back in time to gather the historical figures they are going to use for their report but also experiencing the world and culture of those they're using. The film shows that even though the duo attempted to take the "easy way out" to pass their class, they ended up in a much more difficult (albeit hilarious) situation that resulted in them learning the same material they should have been learning all along. This commentary shows that many paths may lead to the same outcome (studying and doing the work vs. using a time travelling phone booth to take people out of history and nearly dying multiple times), but the effort toward that same reward or outcome is often disproportional (with some paths being much higher risk for the same reward).