Corrected entry: When the rider summons the cold, the window freezes. If window glass were to get that cold that fast it would shatter. The cold does manage to find it's way in and everyone's covered in frost and there are huge icicles in the house. First off, somebody would've woken up if they weren't dead already. Second, icicles need liquid water to grow and they don't grow in extreme cold. Also, even falling icicle's that large would likely injure but not kill someone (the ones that weren't controlled by magic). (01:17:20)
Corrected entry: Will is told that the dark cannot enter the Great Hall unless it's invited. Later, Will opens the door when the rider is faking his mom's voice and the rider comes in, however, just opening the door for someone does not make them a guest nor does it invite them in. (01:25:20)
Correction: This is purely opinion-based. You may not see it as an invite to open the door for someone, but many others would say that opening the door for someone who asks to be let in is the same as a spoken invitation. And apparently whoever placed the enchantments on the Hall thought so too.
Correction: This entry nearly explains itself away: magic. The windows don't shatter because it's magic. The icicles form because it's magic. Frost grows on people without killing them because it's magic.
Phixius ★