Liverpool winger Ibe came off with a suspected hamstring injury in the 2-1 defeat against Crystal Palace and Everton defender Galloway is currently undergoing treatment by the Three Lions' medical team.
Southgate said: "Jordon is being assessed by the club, we're waiting for the outcome of that, hopefully he is okay and can travel, if not maybe we'd have to think about whether there's another replacement to bring in."
"Brendan is being assessed now, he is with us. It's a muscular injury but we don't want to take any chances. Maybe he is okay for Thursday; maybe he is okay for Monday. We don't know."