(Did Pharaoh call for Moses while it was still dark?)

Exodus 10:21 And the LORD said unto Moses, Stretch out thine hand toward heaven, that there may be darkness over the land of Egypt, even darkness which may be felt.

  22 And Moses stretched forth his hand toward heaven; and there was a thick darkness in all the land of Egypt three days:

  23 They saw not one another, neither rose any from his place for three days: but all the children of Israel had light in their dwellings.

  24 And Pharaoh called unto Moses, and said, Go ye, serve the LORD; only let your flocks and your herds be stayed: let your little ones also go with you.

(If not, then he would have then waited until the plague was finished.

But for most of the plagues, did he not speak to Moses in the midst of the plague?

If that is the case here, then he would have called for Moses in the midst of the darkness that could be felt.

That would have been a terrifying thing for whichever servants Pharaoh sent.

We have all heard of people that have been easily lost in the whiteout of a blizzard, or the brownout of a sandstorm.

This would have even been worse, and the servants may not have known if the darkness was permanent or not.

Would they have considered using ropes to connect their way back?

Perhaps they had to send out multiple groups, especially if they were not sure which way to go to find Moses.)