When Does "Bill & Ted's Excellent Adventure" (1989) Take Place?

"Bill & Ted's Excellent Adventure" is a science fiction comedy film written by Chris Matheson with Ed Solomon that released February 17th, 1989. So when is "Bill & Ted's Excellent Adventure" set? 

It takes place in the year: 

1988 AD 

We know this because there's a poster for the first "King Kong" (1976) remake in the background in the bedroom of Theodore 'Ted' Logan's little brother, Deacon Logan. That movie released on December 17th, 1976 so it must be after mid-1976 AD when it would have been first promoted. 

More specifically, Rufus says to the audience during the 2688 AD prologue, "You see, 700 years ago"... "So now I have to travel back in time to help them out." It's clear this is 'the present' of the narrative. 

2688 - 700 = 1988. 

Furthermore, there's a time and place setting title card superimposed over the footage directly telling us it's "SAN DIMAS, CALIFORNIA  1988". 

Additionally, there's a prologue introduced by Rufus after the opening credits like this: "Hi. Welcome to the future. San Dimas, California, 2688 AD". So we can fairly conclusively say it is 2688 AD. We will revisit this time briefly later twice. 

Then, of course, the story involves time-travel to MANY different years: 

First, to a nineteenth century battlefield. Rufus specifically says, "Austria, 1805. The French have just invaded." when Ted asks, "But where are we, Rufus?" and Napoleon's forces did indeed attack Austria in late September of 1805 AD so it is certainly September of 1805 AD. 

Secondly, to 1879 AD the new title card reads "NEW MEXICO  1879" . 

Third, to 410 BC where yet another title cards declares it's "ATHENS, GREECE  410 B.C." 

Then, during the following jaunt through time, Bill S. Preston just says, "England, 15th century." when Henry McCarty a.k.a William H. Bonney a.k.a. Billy 'The Kid' asks him, "Where are we, dude?" That just tells us it's some time during or after 1401 AD and before or during 1500 AD. Ted soon says, "Check it out! Must be the castle of King Henry." The English King Henry IV (1367-1413) died in 1413 AD but his son, the English King Henry V (1386-1422) and grandson, the English King Henry VI (1421-1471) also used the name. So these scenes are unplaceable other than taking place between 1401 AD and 1471 AD. 

Even, in a scene accompanied by a title card reading "VIENNA, AUSTRIA  1901" the main characters so it is most likely 1901 AD . 

Similarly, when they jump back into the time-machine disguised as a phone booth, "KASSEL, GERMANY  1810" ? . Beethoven . 

Next, a short pit-stop in "ORLEANS, FRANCE  1429" ? . Joan d'arc . 

One of these quick time-travel scenes includes the title card: "OUTER MONGOLIA  1209" but, later, Bill says, "It is indeed a pleasure to introduce to you a gentleman we picked up in medieval Mongolia in the year 1269." It's very possible that this scene does take place in 1269 AD. Presumably though, while Bill will one day be excellent, he is very young and just picked up his interest in history about 12 hours earlier. So the omniscient subtitle is probably correct and the short scene takes place in 1209 AD. 

? "THE WHITE HOUSE  1863" ? . The real-world United States of American President Abraham Lincoln (1809-1865) appears in the White House so it must be after he took office in March of 1861 AD and before April of 1865 AD. 

Finally, the almost whole delightful cast of historical figures and our dynamic duo main characters are stranded for a few short scenes in a setting labeled by it's own time and place setting superimposed title card saying: "SAN DIMAS, CALIFORNIA  1,000,000 B.C." We see two Homo neanderthalensis (neanderthals), a real-world different species of human that existed between 241000 BC and 38000 BC. So it might be 1000000 BC but it is truly most likely sometime much later and therefore is actually unplaceable. 

It was adapted to comics in late 1989.