The Match Review Panel has deemed McShane's offence, which occurred in the 12th minute of Thursday’s game at Emerald Headingley, as a Grade D.
That carries a penalty of three to five matches and, if found guilty, means the influential 29-year-old could be out of action until May.
The incident during Castleford’s 21-20 Golden Point loss at Leeds was only penalised at the time but television replays showed clear contact from McShane as he tried to brush off the England scrum-half.
Meanwhile, Myler has been handed a one-match penalty notice for a Grade B dangerous lift on Tigers' Alex Foster later in the first half so he is set to sit out Rhinos' trip to Hull KR on Thursday.
McShane must face a tribunal tomorrow night and any suspension would see the ex-Wakefield and Rhinos player miss Friday’s visit from champions Wigan Warriors and add to the woes of head coach Daryl Powell.
He was forced into starting the player at scrum-half against Leeds after Jordan Rankin became their third No7 to join the injury-list.
The Australian is expected to be out for two to three weeks and with England’s Luke Gale and fellow half Jamie Ellis also sidelined, Castleford could face real selection issues having also recently released former Kiwi half-back Benny Roberts.
Full-back Pete Mata'utia could be moved into the halves as he was in the second period against Leeds with youngster Calum Turner - a replacement at Headingley - possibly starting at No1.
In all likelihood, England loose forward Adam Milner would start at hooker unless Powell - aiming to avoid a third successive defeat - decided to bring teenager Jacques O’Neill in for his first start.