Way to win Rex over, Mark!

I think I can answer Rex’s question in panel 2 with an unequivocal “No!” Mark really has a hard-on for arguing with Rex, but he’s not exactly winning. (By the way, I like Rex’s stink eye in panel 2!) Hmm, I wonder if Mark has lost track of what he is supposed to be doing? Anyway, Rivera shows us that she has seen the first Mark Trail strips (from 1946) when Mark thought Cherry’s pet bear was attacking her. I’ve always felt that Rivera’s Cherry was more like Ed Dodd’s outdoorsy version of Cherry, before she became too domesticated and dependent during Elrod’s drawing tenure.

The other thing I am curious about are those pinkish tabs that appear below Rex’s eye in panel 1 and Mark’s eyes in panel 3. I’ve seen them in Rivera’s drawings before, but I have no real idea what they represent. Any ideas, readers?