Happy Death Day may spend more of its time explaining the slasher mystery than the actual science fiction behind the time loop that forms the movie, but now that the sequel is out, the director finally reveals the clues that fans missed in the first movie.
The director had previously teased that there was a true explanation for Tree Gelbman living her life over and over (and over, and over, and over) again in the first film. But not only was there an explanation behind the time travel, the film itself includes TWO major hints as to why it’s happening. With the sequel Happy Death Day 2U finally revealing the explanation for Happy Death Day’s time loops, the original clues can be spotted and understood.
Fans curious to know more about the logic and quantum pseudo-science on display as part of the sequel’s plot (or who totally missed the real time loop theory at work) should read our full explainer of Happy Death Day 2U’s time loops and ending. But looking specifically at the first film knowing what’s REALLY taking place, the first clue is one that may have stood out to some viewers on their first watch. We’re referring, of course, to the many power outages that take place across the university campus in the hours (and apparently days) leading up to Tree’s murder.
It was these same power outages used by Tree to ultimately get the drop on escaped murderer John Tombs, so there’s a good chance viewers made a connection that was more than mere coincidence. Having seen the second film, it’s explained that the power outages are the result of Ryan’s experiments with a device dubbed the Sisyphus Quantum Cooling Reactor, or “Sissy” for short. He and his fellow students built it with the intention of slowing down time, but inadvertently wound up creating the time loop in the first place.
But even more than the power outages caused by attempted firings of Sissy is the timing. Specifically the power outage caused by Sissy firing at 9:23 pm, which is used as a pivotal make-or-break plot point in both movies. In the first, it simply cut the power. Fans didn’t know that it was also forming something of a Quantum bridge, or an opening that would eventually return Tree back to the moment Sissy fired in her own timeline.
As we said before, these are clearly the easier to spot of the two major clues, since it can be seen over and over, practically forcing viewers to ask what is causing them. But the second, far more brilliant clue paid off in Happy Death Day’s revealed exactly what caused Tree’s time loop… and it was literally the first thing that audiences heard in the opening credits.
As we said before, the more discerning, Theory-loving, science fiction fans may have taken an interest in the unexplained power outages seemingly striking Tree Gelbman’s life at key moments. However, most viewers will probably be kicking themselves over not looking any deeper. And if that’s the case, the the reveal of the second major clue is going to have them outright furious. Well, we shouldn’t really call it the “second” clue at all… since it was literally the first thing that Happy Death Day audiences were shown on screen.
Before Tree wakes up in Carter’s bed, before Ryan comes bursting in, before ANY of the movie technically starts, the director reveals not just the premise of the first Happy Death Day, but its sequel, too. For those who may not remember the opening title cards, the first movie receives a custom Universal logo treatment. It begins the same, with the sun bursting out on a rotating globe, complete with the trumpeting score… only to suddenly be sucked back into darkness, start over, and repeat the motion and sound once more. Take a look at the sequence, embedded below here:
A clever joke playing on the play, death, restart, and repeat format of Tree’s coming journey, right? Actually, director Chris Landon reveals to Insider that one other detail buried in that opening logo sequence is paid off in the sequel:
The second one was actually a sound in the opening credit sequence of the movie, the Universal logo. When the logo repeats itself, it makes a very big crazy sound. That’s the actual device powering off [in the sequel].”
So people actually hear–it’s called SISSY in the movie–the Sisyphus Quantum Cooling Reactor. That’s the sound it makes when it goes off.
As unbelievable as it may seem considering the Happy Death Day franchise’s leap from a comedic slasher movie to a science fiction adventure, the video above leaves no doubt. Even then, the filmmakers knew what caused Tree’s time loop: not simple fate, universal mystery, or a karmic chance to prevent murder. Just plain old tampering with quantum mechanics and the fate of the universe.
The science explored in Happy Death Day 2U guarantees that the opening logos will never be seen the same way again. The same will be true of the film that follows them. It’s a new level of clever winking to future audiences, making it official that Tree’s day was starting with the first(?) firing of Sissy, opening the time loop into the past that she would spend the rest of the day working through, until reaching the Sissy firing the next day… starting the loop from the future to which she would try to return.
There are sure to be more nuanced theories diving into the actual theoretical, quantum physics of the now science fiction movie series, but for now, it’s clear Happy Death Day fans will have plenty more rewatches ahead of them if Happy Death Day 2U is any indication.