1. Not to do full kriah at Alenu in Musaf Rosh Hashonoh, only Yom Kippur (from Mateh Efrayim, hilchos yomim noroim, an ancestor of mine)
2. Having one arm out of the kittel under the chuppah (no idea how this one started)
3. Just kiddush before lunch on shmini atzeres in the sukkah, otherwise not in there on S’A at all. (minhag mishpachas Rashi)