Five-0 and NCIS: Los Angeles were previously set in the same universe when Daniela Ruah appeared as a guest star on Hawaii Five-0. On January 11, 2012 it was announced that CBS would be airing a two-part crossover event between Hawaii Five-0 and NCIS: Los Angeles in May. Initially Chris O'Donnell and LL Cool J were set to appear in Hawaii Five-0 while Alex O'Loughlin and Scott Caan were set to appear in NCIS: Los Angeles However, on March 2, 2012, prior to the crossover's filming CBS announced that O'Loughlin would miss shooting some episodes of Hawaii Five-0 to seek drug treatment related to pain management medication prescribed after a shoulder injury. Due to this he was replaced by Daniel Dae Kim for the crossover event. The second episode of the crossover was the first to be filmed; while production on it was taking place the Hawaii Five-0 script was yet to be handed out. During filming NCIS L.A. creator stated "Crossovers are not easy to pull off when you're working in the same town, and when you've got the other show being shot a five-hour flight away, it's particularly challenging." Reception Critical response Jim Garner with TV Fanatic who reviewed the first part of the crossover said "it was a lot of fun having Hanna and Callen from NCIS: Los Angeles visit the Five-0" and gave the episode an editorial rating of 4.4 out of 5 stars. Carla Day also with TV Fanatic who reviewed the second part said ""Touch of Death" worked well, but the crossover was a bit of a mess. Even though they were tracking the same smallpox, the cases were very different. Back in Hawaii, it was all about Comescu, but then it took an odd shift from Jarrod Prodeman selling to Dr. Holden in Los Angeles" and gave the episode an editorial rating of 4.6 out of 5 stars. Viewing figures United States In the United States the first part of the crossover was watched live by 10.91 million viewers. Within seven days, by digital streaming, DVR recording, and other means of delayed viewing the episode was watched by an additional 3.5 million for a final total of 14.33 million viewers. The second part was watched live by 15.21 million viewers which ranked second in viewers for the night and fifth in the week. Within seven days it was viewed by an additional 3.3