At the end of the "Be Careful What You Witch For" when Prue magically closes the door, there is a wall and staircase behind her, yet the front door of the Manor has been repeatedly shown to open on a long hallway.
When Piper and Phoebe leave to go find Prue, they open the door and it's dark outside and Piper says, "we have to hurry, it'll be late soon" then cut to the next scene and they're driving to the park and it's daylight, as are the following scenes in the manor. Correction: Piper says "we have to hurry, it'll be light soon." This explains why it was dark when they left and daytime when they got to the park.
When Phoebe is stuck floating in the attic and Leo levitates to bring her down, her harness hook on the left side of her jeans are clearly seen.
Leo says genies are tricksters who would do anything to be free. It is also established with Piper's wish that people don't have to say their wishes directly to the genie for it to count. In that case, the genie didn't even have to interact with the sisters to free himself.
When Piper and Phoebe are discussing Prue at 17, Leo asks what she was like. As their whitelighter, he's been watching them their whole lives (a fact Piper pointed out earlier) he shouldn't have to ask questions like what Prue was like.