The full back has had a fantastic season for the Reds and continued his rise to the top by making it into the England 23-man World Cup squad.
"Looking at all the changes Gareth made to the team yesterday, and I know it wasn't big opposition but given how well they performed, I don't think he'll pick the same XI for all three group games".
Rashford unleashed a dipping drive from the right in the 13th minute, that flew past Keylor Navas.
In 2014, Costa Rica practically shocked the world as they topped their World Cup group ahead of Uruguay, Italy and Thursday night's opponents England.
Marcus Rashford has enjoyed the best last six months in a Man United shirt but he has looked at home on the worldwide stage since day one, and judging by his performance against Costa Rica he could be ready to the the World Cup by storm. They joined up late after their Champions League final defeat...
The Manchester United striker, playing alongside Jamie Vardy in attack, was the star of the first hour at Elland Road and capped his performance with a spectacular 25-yard strike.
The friendly was played just 11 days before the Three Lions' opening World Cup match in Russian Federation against Tunisia. Should Alexander-Arnold impress against Costa Rica, Kieran Trippier could lose his place.
England's pressure resumed after half-time, with Navas palming away a fierce Jordan Henderson strike before the resulting corner saw Harry Maguire's header cleared off the line by Bryan Oviedo.
Loftus-Cheek dragged wide from distance before goalkeeper Nick Pope came on for his debut among a swathe of England alterations.
Phil Jones clipped the crossbar with a header but it was Rashford who looked brightest in a positive early spell for England, and it was fitting for him to break the deadlock.
England were unable to find a way to add a third but emerged victorious - and seemingly without injury.