In the hothouse scene, Ianto's right hand is on Jack's left shoulder. After cutting away and then quickly shifting back, Ianto's right arm is now completely trapped against his body by Jack holding him in an embrace with his left arm.
Tosh says until now, Torchwood believed things could only come through the rift one way, however previously, she and Jack were transported back in time in Out of Time and Captain Hart went back through the rift in Kiss Kiss, Bang Bang.