Free-scoring Rangers moved up to sixth place in the Championship with a third consecutive win and they have scored 11 goals in their last three games.
But it was not all plain sailing for Magilton's side, with Derby taking a two-goal lead courtesy of Paul Dickov's first goal for the club and Robbie Savage's superb free-kick.
Adel Taarabt pulled a goal back before half-time and the former Tottenham player was a constant thorn in Derby's side as second-half goals from Gavin Mahon, Jay Simpson and a late Akos Buzsaky penalty sealed the points.
Magilton said: "Parts of our play were very, very good, other bits and pieces weren't so - but how can I fault the lads after that.
"We switched off for both of their goals. The first goal we conceded was a schoolboy one, the second was good execution from the free-kick.
"But our goal just before half-time was crucial and we're playing with great confidence and that showed in the second half when we were absolutely magnificent.
"We were top class for long periods in the half and we ran out worthy, worthy winners."
He added: "I've no idea where this form will take us.
"I'm very much a manager that deals with it game by game but I'm delighted with the direction we're heading in.
"Our progression has been steady. We've skipped under the radar which is fabulous, but we're a very grounded group and we won't be letting a result like this get us too carried away."
Derby manager Nigel Clough pinpointed two moments that proved pivotal in an open and entertaining contest played in front of another 30,000-plus crowd at Pride Park.
He said: "There were two critical things, conceding just before half-time and then again in the 46th minute.
"When we were 2-0 up it was important that we got to half-time and then kept it tight for 10 minutes in the second half but we could do neither.
"For the free-kick that led to their first goal, we should not be giving them away in that position and then the ball should not have gone around the wall at that height. For the second goal the two centre-halves were sleeping in the 46th minute.
"I thought they played extremely well, you saw a side full of confidence who have scored four goals in their last three games and everyone wanted the ball.
"But we gave the ball away far too much all over the place."