After Jack brings the puppy over to the girls, the box he brought the puppy in was placed on the back end of their couch. At one point, it is knocked over, and you can see it falling down to the floor (past Janet). In a few shots, it's back on the table, and none of the characters were in a position to pick it up to place it back there.
In the episode where Janet asks Jack if she's a bad kisser, take a look at Janet when he kisses her. Jack unexpectedly slip Janet his tongue (which surprises the audience as well) and that throws Janet off and shocks her. Her surprised face is not acting, and was really surprised he did that. You'll also notice that when they part, she can't keep a straight face.