Lewis dislocated his shoulder when sliding for an attempted try on a rain-soaked surface at St. Helens and Morris was badly winded in a similar situation after sliding down a slope that runs off behind the goal at Manchester United's Old Trafford.
Boyd admitted there were some concerns by the players but said Mal Meninga and his backroom team had assured the squad everything had been done to improve safety.
"Mal's been pretty good with preparing us," Boyd said.
Kangaroos skipper Cameron Smith and Kiwis captain Jesse Bromwich pose ahead of the Four Nations final at Anfield.
"He measured out the pitch at Coventry and it was a bit shorter and you could tell in London that the distance between the 30 and the 40 metre line was about seven metres.
"At Old Trafford three years ago it was a bit dangerous when you were chasing a kick.
"It's a bit worrying but at the end of the day it's pretty special to play at a ground like Anfield where there hasn't been much rugby league played before."