Franny's Mother, played by Joanna Gleason, sings very badly in the movie and is asked numerous times by her daughter not to sing. In fact, Gleason has a very good singing voice and has appeared in several Broadway musicals, including "Into the Woods".
At the first wedding, Jennifer Lopez's character Maria comforts the bride by complimenting her great thighs. This may be a small reference to the huge media focus on Jen's "big" thighs when she first began her singing career.
In an early scene in Matthew McConaughey's office, he indicates a framed picture of his "sister". The prop is actually a picture of associate producer and choreographer Anne Fletcher, who had a scene in the movie that was cut.