Why does it say "Ya'asu Egel b'Chorev"?
Radak: Future tense is used in place of past. There are many verses like this. It mentions Chorev, for this is where they received the Torah and heard Aseres ha'Dibros, including "Lo Sa'aseh Lecha Fesel v'Chol Temunah" (Shemos 20:4).
Why is Chet ha'Egel mentioned after Korach? It was before!
Malbim: This aggrandizes Korach's sin, which was a feud against Moshe. They said that they do not need [a Kohen Gadol] to be an intermediary between them and Hashem, for they said "Kol ha'Edah Kulam Kedoshim uv'Socham Hashem" (Bamidbar 16:3). This is the opposite of what they said when Moshe delayed descending - they made an Egel, for they said that they need an intermediary!
