Prince Harry and Meghan Markle's son Archie Harrison Mountbatten-Windsor was christened over the weekend. However, many people noticed Queen Elizabeth II and her husband Prince Philip weren't present on the occasion, and the reason why the monarch is reportedly absent is due to the royal couple's "blunder."

Last Saturday, Archie was christened in a private chapel at the Windsor Castle, and the members of the royal family attended the event, including Prince William and wife Kate Middleton, as well as Markle's mother, Doria Ragland. The family photo, however, has shown who weren't present, most notably Queen Elizabeth and Prince Philip.

In a report from the Sunrise News, royal commentator Rob Jobson said the reason why Her Majesty wasn't at the event is due to a "simple calendar error" by the Duke and Duchess of Sussex. The monarch wasn't able to attend her great-grandson's christening because she has prior engagements.

Reportedly, it was Prince Harry and Markle's "blunder" that's why Queen Elizabeth couldn't make it. Robson said the royal couple likely didn't check the date and forgot the monarch has prior engagements. Her Majesty was at the Holyroodhouse Castle in Scotland for this week and then spent the weekend with Prince Philip in Sandringham.

Robson said the Duke and Duchess of Sussex didn't get the diary dates of Her Majesty, and the royal commentator added that as long as the godparents are there - Prince Charles and Ragland - then everything's okay. After all, there are other great-grandmothers out there who have also missed their grandchildren's christening.

Another royal commentator, Melanie Bromley, agreed with Jobson and said this isn't the first time Queen Elizabeth missed a christening and it wasn't a big deal. In a report from E! News, she said the monarch and her husband had already booked to Sandringham, along with her prior engagements.

Bromley added the royal family is no different from other families. They have a big family and couldn't pick a date that would fit with everyone's schedule. Prince Harry and Markle have changed Archie's date of christening; it was originally set for Friday but move it to Saturday as they wanted Prince Charles and Camilla Parker-Bowles to be present since they couldn't make on Friday.

Meanwhile, Markle's father, Thomas Markle, reportedly wished he could have been at his Archie's christening. Robson noted what Thomas said wasn't bad, except that he's likely making a "little bit of a dig" with his ex-wife, Ragland.