We are not allowed to add to G-d's commandments Rashi brings three examples The question asked is why these specific three

Why why the discrepancy in mentioning where the Jewish people were as it states at the end of the book of numbers and as it states at the beginning of the book of Deuteronomy

What does it mean that the book of Devorim was said by moshe on his own?

Aaron's passing is recorded in the Torah because the whole Jewish world mourned his passing which was a very unique occurrence and therefore more than likely it was marked in the years following and therefore the Torah specifically told us the date of his passing

The significance that the date of the passing of Aaron is the only date of the passing of any individual recorded in the Torah. That being the first day of the fifth month

The two tribes that remained in the transjordan mentioned their livestock before their children. Why was this so?

In the war against midyan each tribe gave a thousand and the tribe of the Levites did as well. Unlike all other wars the Levites did not contribute soldiers and each tribe gave a percentage of the male population. Why the distinction?

Why were the laws of taking a vow specifically given to the elders of the Jewish people?

Why does Rashi say the word ram in the plural as Rams when in fact we are only speaking about 1 ram

Contrasting our section the deals with the festivals with the other section in the Torah that also deals with festivals and why there is a different verb used in terms of moshe speaking