Well, perhaps not. In the letters column of Marvel's What If #22, the Watcher himself tells us that Rutland is an artificial nexus of all realities that "fluctuates in size and accessibility." So heroes and villains from the Marvel and DC universes often make appearances there. Visit Rutland on Halloween and there's a good chance you'll get killed or mind-controlled by a supervillain. It happens pretty much all the time.
We get a particularly strong example of this in 1973, when writers Steve Englehart, Len Wein and Gerry Conway inserted themselves into a sort-of Marvel/DC crossover. At the time, Englehart was writing Marvel's Amazing Adventures, which recounted the adventures of the former X-Man Beast (who had only recently mutated again and gotten all furry.) Conway was writing Thor, while Len Wein was scripting DC's Justice League.
In Amazing Adventures #16 (cover dated January 1973 but published in October 1972), Hank McCoy is on his way to Canada as a part of the book's current story arc. But he has himself a little mini-adventure when he stops in Rutland when Juggernaut (who has been trapped in a mystical limbo for some time) is sort of spit out into Rutland himself. What follows is an extended chase scene, with Hank trying to stay ahead of the much-more powerful villain until he can snatch Juggernaut's helmet away and leave him vulnerable to a punch in the jaw. The fight ends with Juggernaut's return to limbo.
It's a fun story, made interesting by the fact that Hank has to out-think rather than simply out-fight the bad guy. But what makes it really interesting is the presence of Englehart, Conway, Wein and Wein's wife Glynis, who are in Rutland for the Halloween parade. Glynis, in fact, is dressed in a modified Lawyer-Friendly version of Supergirl's costume. They witness much of the action (with Englehart in particular ironically failing to recognize Hank McCoy).
During the story, we see a little of the parade, with some DC heroes waving to the crowd. The assumption would be these are locals in costume. But in Justice League of America #103, we learn that this is the real Justice League!
In that story, the Phantom Stranger warns the JLA that evil sorcerer Felix Faust has escaped from prison and is intending to release demonic entities upon the world, starting in Rutland. So the JLA is keeping an eye on things, while hidden in plain sight by taking part in the parade.
The ensuing story has a nice twist, with the Phantom Stranger seemingly allowing the JLA to be defeated by the possessed civilians--some of whom are dressed as Lawyer-Friendly knockoffs of Marvel heroes and all of whom now have superpowers. But the Stranger is really just setting up a magic spell that will save the JLA and drain Faust of his power. When this succeeds, Faust steals Englehart's car for a getaway, only to get pulled over by the cops because of a faulty muffler.
A month or so ago, I reviewed the first Superman-Spider Man crossover. That story was implicitly set in a separate universe from the Marvel and DC worlds--one in which the heroes from those universes co-exist. Here, though, each of the stories is clearly a part of Marvel (Beast, Thor) or DC (JLA) continuity. Now, of course, the writers were just having fun and there's no inherent need to come up with an explanation for how this is possible.
But what fun would that be? The answer can only be that Rutland, Vermont is indeed a nexus of all realities, with our universe co-existing for perhaps one night a year with DC, Marvel or both. That would explain these three stories. Heck, if Rutland is near where Bob Newhart lived in his 1980s sitcom, then this might explain his famous series finale as being more than just a dream!
So, for gosh sake, don't go there. I know the parade looks like a fun event, but you don't want to be mind-controlled into attacking Green Lantern or have your soul sucked out by Loki. It's just not worth it. Continue driving and just find some place outside of town for a nice picnic or something.