Hawley has a sprained ankle and was still unable to train on Thursday, while Reid suffered a groin injury in earlier in the week so did not feature against the Minstermen.
"It was unfortunate that Paul Reid wasn't available. He tweaked his groin on Tuesday and we felt we couldn't risk it so he had a scan on Wednesday," said Iron manager Alan Knill, speaking to the club's official website.
"It has come back okay, but he's still a bit sore with it so he missed training on Thursday."
Hawley suffered his injury against Tranmere two weeks' ago, missing the loss to Stevenage. He will be assessed on Friday.
Michael Collins played 45 minutes as he steps up his return from tendonitis, while Callum Kennedy and Andy Barcham also featured.
"The result wasn't great but the important thing was we got some players on the pitch," added Knill
"It was a good work-out though and it was good for the players to get some fitness."
United did not reveal the score in the behind-closed-doors friendly.