These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Hell Is That Noise: TIPTOE TO THE WINDOW, BY THE WINDOW, THAT'S WHERE IIIII'LL BE! COME TIPTOE... THROUGH THE TULIPS... WITH MEEEEEE!
As well as the cracking sound that always accompanies the demon.
Narm / Nightmare Retardant: The viral marketing for the movie had an Alternate Reality Game called Voice From The Further, about a blog maintained by a woman who also mysteriously fell into a coma as a small child and is now trying to discover what happened to her. Some parts are genuinely creepy, mentioning ill-spirited ghosts and figures like The Redfaced Man, but then let down by obvious photoshop jobs and amateur video. Case in point.
The hula-dance scene.
A lot of people thought the gas mask was funny rather than eerie, same with the little dancing kid.
One of the film's big scary moments is supposed to be when Josh discovers Dalton imprisioned in the Further with the demon, but since the demon has a penchant for listening to Tiny Tim, his infernal lair looks like the set of a Meatloaf video, and he's first properly shown cheerfully sharpening his claws while listening to his favourite tune, it can be hard to take him as seriously after that.
The demon himself can be this. Quoting Cinema Sins: "Why is Darth Maul in this movie?" Also, in the credits, he even goes by the name of "Lipstick Demon".