Kickassia. Almost everyone involved was injured somehow, the worst being cameraman Rob Walker getting a nasty leg injury on the first day, but he was still quite a Determinator as he kept cramming himself into tight places and waiting until filming was over to seek any medical attention. Also, Lord Kat twisted both his ankles, which forced his role to be severely reduced, and the extremely tight four day filming schedule meant that the climax had to be significantly trimmed down, with scenes like Spoony revealing himself to still be Insano never being filmed.
Thankfully, injures were minimal compared to Kickassia. However, the few that did happen created controversy shortly before SK came out. During filming, Elisa of Team NChick was duct taped to a wall and got a little overheated. Somehow this got interpreted as "crucified upside-down" and one of the site's biggest critics used this info to try and "ruin" TGWTG. Thankfully it didn't go anywhere.
While the Brawl wasn't as bad, it still had problems. In a blog post, Lindsey Ellis said that the reviewers had yet to form the sense of camaraderie that there was in later crossovers, plus, among other things, an unnamed reviewer (implied to be That Aussie Guy) spread lies about Lindsey's sex life.
To Boldly Flee had the smoothest production time, but it wasn't without its problems. The biggest hurdle was the majority of the cast filming a 3-hour film in the span of a week, leaving little time for rest. Doug was forgoing sleep and food to finish filming and was getting very emotional while filming his scenes. This was partly due to him incorrectly assuming that he was putting the other actors through too much stress. Post-production was also troublesome, as there were problems uploading the files. This resulted in each part being released every three days rather than once a day as the previous two specials. The stress everyone goes through and the Troubled Productions are why Doug swore off big crossover events and why The Uncanny Valley was an anthology.
That Dude in the Suede's review of the 4th Pokemon movie had to be this for sure. Jesuotaku and Suede were already quite busy beforehand, making scheduling recording quite hard. Not all the details have been made clear, but the suicide of former Channel Awesome contributor Jew Wariohad to have made production awkward. The final cut of the review featured Jew Wario's voice for about the first 3 minutes. It is unknown if it is all of the audio he had recorded or the episode, and he had to be written out using some clever dialogue. His voice is clearly someone else trying to do an impression of him during the last few seconds in order to get him out of the review.
Episodes of The Time... Guys come out very infrequently. Going by the apparent age of the cast and by Word of God, filming can only take place during school breaks. This has actually worked out well; newer episodes usually come out as shorts instead of the less tolerable twenty-minute epics they were originally.
On a smaller scale, the big crossover review between The Nostalgia Critic, Spoony and Linkara for Alone in the Dark (2005). To begin with, Doug Walker had lost his voice the day before Spoony and Linkara arrived in Chicago (hence the use of text-to-speech). Secondly, construction work was being done outside Doug's house, so they had to film the review in Doug's basement. In addition, they didn't decide which Uwe Boll movie to review until the day they started writing. Spoony gives the scoop here.
Similarly, not as bad as the other examples, the MA Gfest review of The Last Airbender turned out to be incredibly difficult and rushed. A detailed explanation of all the problems and issues is in the commentary, but, for starters, that shot of the DVD case with The Last Airbender in it hitting the ground which lasts less than one second? It took them something like fifty takes to get that one shot.
Doug Walker and Lewis Lovhaug have both referred to their crossover review of Superman IV: The Quest for Peace as a cursed review. Several introductions were filmed and scrapped (in one instance, the footage filmed around the same time as the Alone in the Dark (2005) review was lost), and it kept getting pushed back after Walker did a Top 11 countdown of the stupidest moments of the Superman film series.
It was mentioned that a few stories in the Metamor Keep universe fell flat on their faces because of this. One author suffered a brain aneurysm, and another came down with pneumonia.
The Fan Film series BIONICLE: The Next Generation currently resides deep in Development Hell because of this. It started out as an ambitious 3D animation film project on the BZ Power forums, shortly before the forum server crashed. The project was moved to a new site, and it was decided that instead of feature-length films, they would make a series of shorts. The modeling had to be started over because the older models suffered from problems. Then, the project leaders left one by one, along with many other disillusioned members. When the BZPower forum came back, the community branded the project a futile undertaking. Since the team struggled with the 3D CGI, they split into different animation groups. Only the 2D team managed to get a test video done, effectively proving that the 3D angle has been doomed from the start. The new project leader then tried to sort out the whole thing and start over with more realistic goals, before leaving to pursuit a more fruitful endeavor. Currently, it seems that the project's fate rests in the hands of the still-working 3D team.
The earlier Quest of the Toa fan-movie has met a similar fate. Production was well underway with a big buzz surrounding the would-be voice actors and the script receiving tons of rewrites due to plotting difficulties. Then, the animation files got lost, and the project, which had been aiming for a late-2006 release date, was canceled in 2007. It resurfaced a few years later with a new and improved models, but went under again in 2010. Given that it was to be made by one person who did everything from directing to modeling and animating, and the fandom had become distilled and disjointed by that time, this is understandable.
A tiny version involving Rooster Teeth: one episode of "Let's PlayMinecraft" ended up having being restarted from scratch when a brief power outage killed their X-Boxes and the recording footage was lost. One of the guys playing, Jack, was very distraught because he was in the lead in that episode's game and having to restart meant losing everything.
Another Dead Hero had himself a rough case of this with his first episode Children of the Corn III: Urban Harvest, which due to not only computer troubles with his editing software going haywire, but also the finished episode becoming so corruptible, he couldn't save it, making it a lost episode. It took him till a couple more months before he released his first official released review, part one of Necronomicon: Book of the Dead. Though, now he's kinda ran into this again, due to losing the camera he used to film the episode and the next two.