It didn't have any ejection port ....but we're all familiar with at least one brand of centerfire handguns, popular with law-enforcement and military folks, without any ejection port because it uses an open top slide design.
The vertical lines you see here ....
...I don't think they are vents in a grill on the weapon's heating and air-conditioning system. Looks like those are grip-enhancing grooves the back of a slide.
A slide that moves.
Reising .22, by the same designer as the Reising SMG’s. The Beretta flip up barrel guns, the Steyr Pieper pistols, and the Dreyse 1907 also share this type of design.