According to Loki director Kate Herron, the production didn't need permission from Ant-Man director Peyton Reed to make a reference to Yellowjacket in the series.
The information comes from an interview with ComicBook.com's Phase Zero podcast, where Herron explained the reference only required approval from Loki co-executive producer Kevin Wright. "So that was actually a pitch from Dan DeLeeuw, our VFX supervisor and no, maybe it went to him," she said. "But, like I said, so Kevin Wright, our executive producer, he was like sort of our Marvel gatekeeper. That's kind of how they do things, so basically he would be across all that kind of stuff."
"I assume behind the curtain [Wright would] be checking, was everything okay with Kevin Feige and that it didn't unravel anything for anything else," Herron said. "But no, I think generally though, across Marvel and everyone, it was just fun, right? It was just a lot of goodwill to have fun with it and give a lot of kind of fun Easter eggs. So, yeah."
The reference occurs in Episode 5, "Journey Into Mystery," as the camera pans over the barren landscape at the "end of time." There's a quick glimpse of a massive helmet lying near the hill where the Loki variants' secret bunker is located. The helmet is an incredibly rusted version of the one worn by Ant-Man villain Yellowjacket, presumably from a variant of the antagonist sent there by the Time Variance Authority. This variant also seems to be able to expand himself using Hank Pym's technology, a feat that was only accomplished by Ant-Man AKA Scott Lang in Captain America: Civil War after intense training.
Herron explained that producers like Wright were how Easter eggs like the one with Yellowjacket were communicated across Marvel Studios productions. "So basically every filmmaker has a sort of, you work with an executive producer from Marvel," she said. "[Wright] would have those internal conversations and then he would come back and be like, 'This is anything we need to shift from that bigger multi-verse conversation.'" She went on to explain how Wright's direction resulted in changes to Miss Minutes' TVA introduction video as well as when He Who Remains explained his story and past. "I think that was, we had an idea, but it was sort of always evolving based upon the ripple effect of the nature of the beast basically," she said.
Loki Season 1 is available to stream on Disney+. A second season is currently in development.
Source: ComicBook.com