Daylight at night?

Is anyone else bothered by the daylight in the night scenes?

It's the evening, since we cannot be seen together during the day, so we walk the exotic ruins at night--and fluffy white clouds fly across the bright blue sky.

I wish you could see this garden during the day, he says, waving his hands at a scene that appears to be fully daylit. He talks about the moon, but it sure doesn't look like moonlight to me.

My best guess is that there were budget constraints and they couldn't afford to shoot at night. Does anyone have a better conjecture?

Don't get me wrong, I still think it's a wonderful movie.