Part of the core premise of the show is that the earthbound spirits don't see the light until they're ready to move on, yet Sarah says she sees the light but doesn't want to go into it yet because she's worried about her parents. Since she's clearly not ready to go into the light, she shouldn't be able to see it in the first place.
Melinda says ghosts haunt places that are familiar to them, even though she was previously adamant that places aren't haunted - people are.
In S1 E13, Jim has to cut Melinda's hair when it gets caught in the garbage disposal. In this episode it is magically long again.