Marg Helgenberger will be reprising her role as Catherine Willows for the 300th episode of “CSI” tonight, and she recently sat down with TV Guide to talk about some of the more memorable moments in the series.

Although the show focuses on a lot of grisly, dark, and sad stories, there are also some lighter moments between the characters which have stood out over the years. Helgenberger–along with the show’s executive producer, Carol Mendelsohn–says that many of those episodes are ones which include guest stars, such as country star Taylor Swift and Liev Schreiber. But one in particular stands out to Helgenberger because of an element she wasn’t familiar with beforehand: adults dressing up in furry costumes.

“I didn’t know much about this world, so before we shot the episode, the director and I went to an event where people came wearing tails,” said Helgenberger. “A lot of the extras we used were actually into that. God bless them.”

The show has not only managed to keep its large and loyal fanbase over the years, it has only grown in popularity. Relative newcomer to the show Ted Danson says that’s because the writing is so good.

“It’s pretty rare that a show does 300 episodes and is still one of the top one or two in the world,” he said. “The writing attracts the good actors, and then you get the great directors, but it starts in the writing.”

Mendelsohn picked her top ten episodes, some of which include cases that never got solved; in fact, tonight’s episode will flash back to one of those cases. The show will air on CBS at 10 p.m.