While there is very little info to go on at this time, it appears that Nintendo was shooting something at Universal CityWalk in Hollywood yesterday.
Twitter account @insideuniversal tweeted images of what appears to be a very small Mario themed set in front of a stage, and a sign that says “HOT SET!”, claiming that “Nintendo Denizens Group” was currently filming.
Nintendo is filming something at CityWalk Hollywood. Hmmmm pic.twitter.com/BzFlRPy3Ld
— Inside Universal (@insideuniversal) July 10, 2018
The image in the tweet makes it appear to be a rather small production, so it could very likely be for some sort of announcement or promotional material for the Super Mario Bros. movie, the Nintendo theme parks, or both. We will be sure to post an update as soon as we have more information.