"Isn't she adorable?" the new mom doted as the photo was flashed up on the screen.
However, the image was actually just a composite photo of Mendes and Gosling's faces. "She looks like both of you," Ellen joked. "I mean really, she looks like both of you doesn't she? It's hard to say who she's more like."
Adding to the joke, Mendes quipped, "Oh My God! I can't stop staring."
Ellen was quick to compliment the actress -- who was donning a red Jacquard Maria dress -- about her post-baby physique. What's her secret to slimming down? "You know, breast-feeding," she revealed. "It really does help to shrink your uterus back to normal size. It does! I know it's a really weird thing to say, but it does."