Nathan Fillion and Susan Sullivan share a sweet moment behind the scenes on Castle Season 6 Episode 6, "Get a Clue"

We don't know his name but The Goonies was definitely the '80s! Still, we can't get enough of seeing Nathan Fillion and Jon Huertas in their '70s costumes.

Production Designer Alfred Sole on becoming clueless. EP 606 was really exciting for me. I love going back in time and designing period. We did a lot of research and ultimately it was as fun as the Da Vinci Code. There were so many clues that we had create to after awhile I became clueless."

A shot of the always beautiful Stana Katic from Castle season 6.

There wasn't much smiling going on for these sister during Castle Season 6 Episode 19 but it's nice to see Penny Johnson Jerald and Salli Richardson-Whitfield looking so happy behind the scenes.

Castle Production Designer Alfred Sole shares some of the challenges of filming. "This is the crime scene burn set. Sometimes sets like these are harder to do than an actual finished sets. We had to build this one first and then destroy it. Believe it or not there were many many hours of scenics painting walls to make them look burnt and scorched. We also had to actually burn a lot of stuff, furniture etc. We started on the studio lot until people started complaining about the smell and moved everything being burned to a different location. I'm really proud of this set. I think it cane out great."

100 Episodes of Castle was definitely a reason to party. Hopefully we'll get to celebrate 100 more.

If only this beautiful vehicle had been able to drive our happy couple off into the sunset. Sigh. Fingers crossed we'll get that some time soon in Season 7.

Apparently things can get a little rough behind the scenes when Andrew Marlowe doesn't get his way!