Mistakes in Ihram
1. Some pilgrims coming by air delay their Ihram (i.e., state of consecration to Hajj or Umrah) until they reach Jeddah Airport and then assume Ihram there or at any other point nearer to Makkah, thus surpassing the Miqat (i.e., site of assuming Ihram) on their way.
Narrated Zaid Bin Jabir: I went to visit Abdullahi Bin Umar at his house which contained many tents made of cotton clothes and these were encircled with suradik part of the tent. I asked him from where should one assume Ihram for Umrah, he said Allahs messenger (SAW) had fixed as Miqat (singular for Mawaqit) Qarn for the people of Najd, Dhul- Hulaifa for the people of Madinah and Al – Juhfa for the people of Sham
Thus, everyone who passes by or becomes parallel to a Miqat on his way, whether by air or on land, while he has the intention to perform Hajj or Umrah (i.e., Lesser Pilgrimage) should assume Ihram at that Miqat. If he surpasses it and assumes Ihram at a place closer to Makkah, then he will have missed one of the obligatory rituals of Hajj and should offer a sacrificial animal in expiation. It is noteworthy that Jeddah is not a Miqat for those who do not live in it and those who assume Ihram in it.
SahihBukhari 1522 Book 25, Hadith 10 Vol 2, Book 26, Hadith 597
MISTAKES IN STAY AT ARAFA
2. Some pilgrims think that during stay at Arafa, they should see or climb the Mountain of Ar-Rahmah, and to do so, they impose on themselves huge difficulty and danger. There is no need to overdo it: All is needed is just to be present anywhere in Arafa, as the Prophet (PBUH) said, “And all of Arafah is the place of standing, and avoid the Valley of Uranah”. [Authenticated by Al-Albani]
«عرفة كلها موقف، و ارتفعوا عن بطن عرنة» صححه الألباني
It makes no difference to see the mountain itself or not. Also, some turn their faces to the Mountain of Arafa when supplicating, while they should do so to the Kaba.