you like it darker

so in stephen king's new book you like it darker, in the fourth story on page 174 there is a quote that says, "there's an action figure on the passenger seat that he recognizes, thanks to darla jean. it's elsa oldenburg from frozen." 

this bothers me so much because there is no official account of that being elsa's official last name. like when you google "what is elsa's last name," there are so many different answers, but oldenburg does show up in a single reddit post. furthermore, upon googling "elsa oldenburg" there are a couple of fanpages and stuff, but the first result is the great multiverse wiki (which led me down a whole other insane rabbit hole, like why is elsa a jedi, what happened between her and goofy where she had to rekindle theire friendship. it's wack). like there's nothing implying that's actually her last name in disney canon, and i never heard of her having a last name in any other context, so it's just weird to me a last name would be included at all.