Image Credit: Rose Peterson / Storyful.San Francisco's Fourth of July celebration got an unexpected guest star this year, and it wasn't a marching band or a hot dog eating contest. It was a fleet of Waymo robotaxis, and not all of them behaved the way you'd want a several-thousand-pound vehicle to behave around a crowd of people. Between a self-driving car that rolled straight over lit fireworks without so much as a flinch and a cluster of Waymos that got stuck in traffic until their batteries gave out, it was a rough holiday for the folks running the show at Waymo headquarters.For anyone who has ever white-knuckled it through a holiday crowd with fireworks going off at ankle level, you know the instinct is to swerve, stop, or at least slow down and reassess. One passenger, Rose Peterson, was riding in a Waymo with her fiance when the car did none of those things. It simply drove over the fireworks in the street like they weren't there at all, no braking, no hesitation. Peterson said the moment left her shaken, not just for herself but for anyone standing nearby who could have been in the path of whatever happened next.As if that wasn't enough excitement for one night, several other Waymos in the area got tangled up in gridlock so severe that people started climbing out of their own cars to yell at the confused robotaxis. One driver who got caught in the mess said he sat there for two hours before Waymo employees finally showed up to sort things out. It's the kind of scene that makes you wonder if the cars were just as ready for the holiday to be over as everyone else stuck behind them.AdvertisementAdvertisementHere's the thing about self-driving technology: it's remarkable when it works, and it's a very public headache when it doesn't. This latest string of hiccups adds another chapter to a year that's already had its share of Waymo headlines, and it's worth taking a closer look at what actually happened.What Happened on the Streets of San FranciscoThe firework incident took place in the middle of the city's Fourth of July festivities, when illegal fireworks were set off in a street where a Waymo happened to be driving with passengers aboard.Rather than treating the pyrotechnics as an obstacle, the vehicle carried on as if nothing unusual was happening. Thankfully nobody was hurt, but the moment was enough to rattle the people inside.The Great Waymo Traffic JamSeparately, and seemingly unrelated to the fireworks incident, a group of Waymo vehicles found themselves stuck in heavy holiday traffic.AdvertisementAdvertisementWaymo says the extreme congestion disrupted the vehicles' normal operations, and some of the cars simply ran out of charge while idling in place, turning a busy street into an impromptu robotaxi parking lot.Not the First Time Waymo Has Made HeadlinesThis isn't an isolated blip. Waymo vehicles have made news before for unusual behavior, including one that reportedly drove into an active police scene.Waymo has acknowledged the July 4th incidents, noting that a separate unoccupied vehicle was also involved in the day's events, though details on that one remain limited.Where This Leaves Riders and OnlookersFor now, Waymo hasn't announced any major operational changes in response to the holiday's events. Self-driving technology continues to roll out in more cities, and incidents like these are likely to keep making headlines as the fleets grow and more people share their experiences on video.AdvertisementAdvertisementIf you're planning to hop in a robotaxi for your next outing, it might be worth keeping an eye out the window, just in case the car isn't as observant as you'd like it to be.If you want more stories like this, follow Guessing Headlights on Yahoo so you don't miss what's coming next.