From the RFL website:
Oxford - Brooker, Nathaniel, Fleming, Burnett, Withington, Allan, Flintham, Igbinedion, Cillimore, Nicholson, Hoggins, MacDonald, Canterbury, Greene, Pickles, Cryer, Backhouse, Carter, Griffith

So that's probably:
Marcus Brooker, Josh Nathaniel, Scott Fleming, Harvey Burnett, Adam Withington, Danny Allan, Adam Flintham, Dan Igbinedion, Chris Cullimore, Aaron Nicholson, Andy Hoggins, Curtis MacDonald, Casey Canterbury, Charlie Greene, Jack Pickles, James Cryer, Ryan Backhouse, Errol Carter, Harry Griffith

Dual reg - none
Loan - Aaron Nicholson, Chris Cullimore (both Keighley)

Compared to last week:
Out - Jordan Gill, Nathan Kitson, Jordan Siddons, Santino Decaro
In - Andy Hoggins (so not playing for Germany?), Jack Pickles, James Cryer, Harry Griffith

Newcastle - Reudiger, Fox, Olpherts, Brown, Blair, Kittrick, Hardcastle, Rennie, Simons, Kilday, Aldous, Clarke, Paterson, Thorburn, Luckley, Payne, Parker, Young, Celerino

No time now to go through that list properly, but it includes Josh Kittrick who played for Oxford last season on loan from Doncaster.