During the bad storm when the lights go out at Eastland Mrs. Garrett says "Oh no, not the electrility, too" instead of "electricity".
When mrs. Garrett is pushing the horse outside, the lead rope can be seen at a firm downward angle, indicating someone is holding the horse from coming further into the room.
When Mrs. Garrett goes outside to retrieve the wet newspaper, you can clearly see it is copy of the Los Angeles Times, which would be highly unlikely to be freshly delivered as the daily newspaper to a school set in Peekskill, New York.