How about…
Eucharistic ministers (ordained or not) changing the words of Communion to “Brother, this is the Bread of Jesus for You” or other bizzare forms. Am I even supposed to say “Amen” to that???
Announcements made by parishoners that go on for 10 minutes between the post-communion prayer and the dismissal.
Cantors who don’t sing well (even though they try hard!). And then there are the ones who sing well, but didn’t bother to look at the music beforehand (like the guy who sang the Exultet at the Easter Vigil I went to this year, and basically improvised the parts of the melody he didn’t know).
And then there was my sister’s former parish, where the Easter Vigil featured black lights in the choir loft, with glow-in-the-dark liturgical dancers set to a tribal drum beat!