Just ten minutes into the match the Dutch defender was clattered by the Everton goalkeeper as he attacked a free-kick.
Van Dijk was adjudged to be offside but VAR still looked at the decision and decided not to penalise Pickford.
Van Dijk, however, had to be replaced by Joe Gomez as he was injured from the incident, and McManaman thinks Pickford was lucky to get away without punishment.
"The challenge here on the Van Dijk injury... I'm very surprised because he could have easily been sent off for this challenge," McManaman said.
"I'm very surprised that it's all just been forgotten about in the offside situation."
The scores were locked at 1-1 at halftime.