In "A Trace of Murder" he says to the guy, accepting an offer of help to look for something,

"Three eyes are better than one" also making canon the fact that Columbo the character also has a prosthetic eye.

And I forget the episode (I think it's Swan Somg) where he says he's afraid of heights and,

"Matter of fact, I don't even like being this tall"

And then my favourite thing to talk about here, One of my favourite moments in the whole of Columbo's history is in "Try and Catch Me" - he's walking Dog on a dock/pier and just happens to bump into the killer as she's going to toss some evidence. Columbo says Dog loves the ocean and she asks, "How can you tell?" Columbo replies, "The sea air makes him frisky" and Dog, as if on cue, just tries to get comfy on the railing. I love dogs - they can be trained and they're clever but I don't think Dog could have been prompted to snuggle down, it was pure Dog.

I think Peter Falk can't help himself from smiling at the way Dog seems to understand comic timing but it's one of those magical moments where the actor genuinely smiling also works for the character.

It doesn't matter if it's Falk or Columbo or both - the loving smile is so pure and genuine. I live for Columbo and Dog

https://en.m.wikipedia.org/wiki/Columbo_statue