I'm still confused about the window vs the roof! At the beginning it showed that the sister jumped from the roof but then later on it was from the office window. I don't know if I blinked & missed the explanation or simply zoned out but was that actually explained or was it just a continuity error? Because I don't remember that being explained. Could someone please clarify as it's bugging me. Thanks. 
But is it a continuity error or was there a deeper explanation? Since at first they showed her jumping from the roof but in the end everyone says she jumped from the office window. I don't remember it being explained but I'm wondering if I missed it.
yeah!! at first they showed her jumping from the roof but the truth is she jump from the office window of her boss. . .and based on my own understanding I think they made it look like she jump from the roof to hide the truth coz there's something reason about the father of the boss or about the boss exactly. . .hmmm. . .  I don't remember. . .maybe about his father is running to politics or hmmm .. . . something before that running to politics reason. . . all I remember there's some reason. . . for my own opinion I think that's the explanation and its not a continuity error...

     (I'm sorry for the wrong grammar...????????)
I could be remembering wrong: but didn't they (the company) say she jumped from the roof? Like it was explicitly stated that's what the company said happened. She jumped from the roof.

It could have been part of the original story/plot to have it revealed "no she didn't jump from the roof from but she jumped out of Hwan-gi's office window" and then drag a few episodes with typical dramaland misunderstandings and finally finish with: "she actually jumped out of Hwan-gi's office because of *this*".

It went through major re-writes at the end of the 2nd(?) week and actually was off-air a full week because the drama was being received poorly. Perhaps they had a story in place but the changes destroyed that and created continuity errors like the one you are bringing up.

But it could also be a simple continuity error from the very start (re-writes or not) like you and others have said.