WHEN LOSS MEETS SCIENCE AN UNSTOPPABLE CREATION ARISES - VIK SAHAY GUEST STARS - Deadly attacks on a team of scientists lead Nick (David Giuntoli), Hank (Russell Hornsby) and Wu (Reggie Lee) on an investigation unlike any they have had before. Meanwhile, as the research continues into the origins of the cloth, Monroe (Silas Weir Mitchell) and Rosalee (Bree Turner) learn that Eve (Bitsie Tulloch) is still feeling the after effects of the death grip. Elsewhere, Capt. Renard (Sasha Roiz) reaches out to an old friend to get answers to the origins of the symbols drawn by Diana.
In an exterior shot of Overton Medical Center, a Philadelphia ambulance is seen, rather than a Portland ambulance.
Several past and present Grimm crew members are referenced throughout the episode:
When Renard looks up Dasha Karpushin in his contacts on his computer, of the names that are seen, George Adams was a production assistant and travel coordinator (seasons 1-3), Ruth Adelman is the supervising sound editor (seasons 3-6), Paul Alary was a set production assistant (seasons 1-2), Danny Alfaro was a production assistant (seasons 1-2), Chris Alley was an electrician and lighting technician (seasons 1-3), Rick Anderson was a camera operator (season 4), Cory Armstrong was a rigging electrician (seasons 3-4), Kara Stanford was a set costumer (season 4), Matthew Karchesky was an original member of the crew's transportation team, Benjamin Kauffman was a set dresser (season 1), Geoff Keller was a construction location foreman (seasons 1-5), Ken Erck was a special effects foreman (season 1-5), Sean Kennedy was an art department buyer (season 1), and Kayla Kilby was a production assistant (season 2).
Listed as a reporter for an online article in The Meriwether Review, Natalie Walker was a production assistant (season 3). On the online listed faculty directory for Meriwether University's College of Biochemistry, Becca Letourneau is a driver in the transportation department (seasons 1-6), Joseph Faltyn was a production assistant (seasons 4-5), Angela Smith was a set decoration buyer (seasons 1-5), Janet Price is a makeup artist (seasons 3-6), and Clark James (referenced as "James Clark" in the episode) was a visual effects supervisor and production executive (seasons 1-5).