Contradiction with Amos 3:7
This verse states that God reveals His secrets to His prophets, whereas Daniel 8:2 implies that Daniel was initially puzzled by his vision.
Amos 3:7: Surely the Lord GOD will do nothing, but he revealeth his secret unto his servants the prophets.
Contradiction with Daniel 12:4
This verse suggests that certain visions or understandings are to be sealed until the end, which can seem contradictory when compared to Daniel 8:2's revelation.
Daniel 12:4: But thou, O Daniel, shut up the words, and seal the book, [even] to the time of the end: many shall run to and fro, and knowledge shall be increased.
Contradiction with 1 Corinthians 14:33
This verse tells us that God is not the author of confusion, yet Daniel 8:2 can be seen as confusing due to the symbolic nature of the vision.
1 Corinthians 14:33: For God is not [the author] of confusion, but of peace, as in all churches of the saints. [confusion: Gr. tumult, or, unquietness]
Contradiction with Ezekiel 28:3
Suggests wisdom and understanding, while Daniel 8:2 implies a lack of understanding initially regarding the vision.
Ezekiel 28:3: Behold, thou [art] wiser than Daniel; there is no secret that they can hide from thee: