What's the biggest red flag/warning sign you have seen at someone's wedding?

Not me but my friend was at a wedding and when they did the "does anyone here have a reason these two should not be wed" part, the crowd broke out in laughter.

I went to a wedding where they played Bittersweet Symphony as she walked down the aisle.
It always felt slightly offputting.
...And then the groom's mom made a speech about how love was like a dog, which had some sweet sentiments about loyalty in there. But also... vaguely shady.

The groom sneezed during the first dance with the bride.
I've been to relatively few weddings and they've all worked out pretty well I suppose.

Brides family said they don’t drink so they didn’t want to pay for the open bar then they drank more than anyone in our family

I was sitting in during the vows ceremony of my own wedding (everyone told me I should get married, and the groom told he would pay for everything).
When it came to the "do you take thee, to be your loyal wedded..." part, I said "yes", as per the original plan.
When it came to his part, the best man came in out of nowhere and asked me to say thank you for this wonderful wedding. I stared at him, but then the groom himself starts going on about how I'm ungrateful for all that he's done for me, and that without his support there would be no wedding at all.
I'm dumbfounded, the groom was the one pushing for the wedding beforehand, promising unwavouring support for it and now it's my fault?
At this point the groom and his best man, hold hands and declare that the wedding is off, and that they're off to some russian night club to dance off my toxicity.
Motherfucker, I didn't ask for any of this. If I recall, you were marrying me to piss off that night club owner in the first place, and now you're suddenly best buddies with him and putting the whole wedding on me? Asshole.
- Someone also asked why you weren’t wearing a wedding dress too, right?
  
  I will wear a dress once the wedding is over!
- Were you in the Oval Office yesterday?
  
  Worst gay wedding ever
- Did you… “sign the minerals deal” after, as the kids say these days?
  
  Kind of have to at this point, but I'll make him work for it
- What.
  The.
  Fuck.
  
  I think that about sums it up
- Yo, what the fuck?
  Can I buy the movie rights to your life?
  
  Is $3.50 a reasonable price?
- At this point the groom and his best man, hold hands and declare that the wedding is off, and that they’re off to some russian night club to dance off my toxicity.
  Honestly, sounds like you dodge a severe gun shot wound right there. Instead you walked away with a minor gun shot wound.
- This sounds like a whole forest fire of flaming red flags.
- Is it over?

Fist fight between the two families in the evening. Marriage annulled within 2 days.
Father-In-Law (divorced) giving a drunken speech about how marriage is a mistake, followed by his ex-wife / mother-in-law giving a drunken speech about how marriage is a mistake and how the bride is not good enough for her son. Divorced within a few years.

Was a +1 to a friend from when we were in primary (grade) school. It was her cousin getting married. When they walked in for the reception, the groom seemed off. The suit he wore, how he wore it, the whole setup seemed off. My friend was a bridesmaid.
When finally they could mingle, she came and sat with me and asked me what I thought. I told her something was off. Now, you need to understand, me and my friend are frank with each other and hold no punches.
She scrutinized the setup and disagreed with me. We agreed to disagree and enjoyed the rest of the party
The couple divorced 6 months later.

The slideshow of the lives of the couple included photos from a Black Lives Matter protest. One of the two getting married is a cop. Then I noticed Thin Blue Line decor around the gift table. The other half of the couple is Black.
- While I agree that seems absurd, people can have more than black and white views outside of American politics and Reddit, which I hope lemmy has. There must be some cops that want to do better, though I barely would believe them.
  
  There must be some cops that want to do better
  I don't think they'd have thin blue line decor though...
- Have to ask are they still married?
  
  Yep. And adopted a white baby. Like, intentionally, specifically a white baby.

Was best man for a friend and the whole time during the ceremony and after i felt like this was a tedious chore to them or at least for my friend. Didnt take long until the talk of divorce started.

My mom liked her boyfriend because he was softspoken. During the ceremony he spoke to the officiant instead of her and she realized that his gentle speech pattern was really mumbling. Nice guy and they remained close friends until he passed, but not really romantic.