The elephant in the room is the claim these mistranslations are somehow needed for functional equivalence, but that is obviously not true. The NIV uses omitted words, added words, and different word meanings to alter the message which of course results in functional non-equivalence.
Mistranslation in the NIV
1) Isaiah 12:3 the omission of the conjunction should read, "therefore"
2) Mark 1:41 Jesus was indignant should read, "moved with anger."
3) John 1:16 does not seem any more flawed than many other translations, what the text actually says is "And out of His abundance we all also obtained grace against grace."
4) John 21:5 friends should read, "children."
5) Acts 13:50 "leaders" should be italicized to indicate an addition to the text.
6) Romans 3:25 sacrifice of atonement should read, "propitiatory shelter."
7) 1 Corinthians 16:13 "be courageous" should read, "act like men."
8) Ephesians 2:3 deserving of wrath should read, "children of wrath."
9) Colossians 1:28 the omission of "every man" (or every person) reduces the force of the teaching that the gospel is understandable to every person.
10) 2 Thess. 2:13 to be saved should read, "for salvation."
11) 2 Thess. 3:6 who is idle should read, "who leads an undisciplined life"
12) 1 Timothy 3:16 appeared in the flesh should read, "revealed in the flesh."
13) Titus 3:4 love should read, "love for mankind."
14) Hebrews 10:14 sacrifice should read, "offering."
15) James 2:5 to be rich in faith should read, "yet rich in faith."
16) 1 Peter 4:6 those who are now dead should read, "those who are dead."
17) 1 John 2:2 atoning sacrifice should read, "propitiation."
18) 1 John 4:10 atoning sacrifice should read, "propitiation."
19) Rev. 13:8 from the creation should read, "from the foundation."
20) Rev. 22:21 be with God's people should read, "be with all."
21) 1 Samuel 15:19 the Lord should read "the voice of the Lord."
22) 1 Samuel 15:20 the Lord should read "the voice of the Lord."
23) 1 Samuel 15:22 the Lord should read "the voice of the Lord."
24) Philemon 1:6 the verse should read as follows: "I pray that your participation in the faith may be effective in deepening your understanding of every blessing that belongs to you in Christ."
Examples 1, 9, 13, 21, 22, and 23 document omission of words or parts of words.
Examples 5, 15, and 16 document addition of words.
Examples 2, 3, 4, 6, 7, 8, 10, 11, 12, 14, 17, 18, 19 and 20 document replacement of the inspired word with a different word or different words.
Example 24 documents a translation devoid of meaning, just an array of disconnected phrases.