The actress praised writers for the "phenomenal job" they did with her character Bernadette's wedding to Wolowitz (Simon Helberg), which in recent episodes has been put in jeopardy by his NASA mission.
"All I'll say is [there's a] scene [that] is super emotional," Rauch told TV Guide. "I always loved those scenes where the whole cast is together and this one is definitely one of my top favourites, if not favourite.
"And the scene is so wonderfully written. I just think the writers did a phenomenal job with the outcome of Howard's dilemma... I think this episode really shows the love the characters have for each other."
Rauch also claimed that she would be okay with Berndatte and Wolowitz failing to marry, saying: "I think it's easy when you couple people off to write within the relationship, but there's more to all of us than our personal lives."
She continued: "I had no idea what the plan was until I got the script. When I read it, I read it like I was a super-fan at a live taping. There was crying, there was an 'Oh my God!' There were lots of 'oohs' and 'aahs' and 'Oh, no! Ugh!' When I finished, I was like, 'That's how it should be'."
The Big Bang Theory season finale airs in the US tonight (May 10) at 8/7c on CBS. New episodes air in the UK Thursdays on E4.