Although the original texts of the Bible were inspired by God and are without error, the same cannot be said for later copies of the texts or translations made from them. Translators are human, and many have allowed their own religious biases to influence their work. Usually such mistranslations are relatively minor, but in some cases they are major blunders and promote erroneous teachings and doctrines.
One such blatant error, made by translators of the King James Version, is found in Acts 12:4 Acts 12:4And when he had apprehended him, he put him in prison, and delivered him to four squads of soldiers to keep him; intending after Easter to bring him forth to the people.
American King James Version×, where the word Easter is used. In the original Greek, this word is pascha and refers to Passover, not Easter. Passover is a biblical festival mentioned in Exodus 12:11 Exodus 12:11And thus shall you eat it; with your loins girded, your shoes on your feet, and your staff in your hand; and you shall eat it in haste: it is the LORD's passover.
American King James Version×, Leviticus 23:5 Leviticus 23:5In the fourteenth day of the first month at even is the LORD's passover.
American King James Version×, Matthew 26:2 Matthew 26:2You know that after two days is the feast of the passover, and the Son of man is betrayed to be crucified.
American King James Version×, Matthew 26:17 Matthew 26:17Now the first day of the feast of unleavened bread the disciples came to Jesus, saying to him, Where will you that we prepare for you to eat the passover?
American King James Version×and elsewhere in the Scriptures. In the New Testament pascha is used 18 times and is translated correctly in the King James Bible as "Passover," except in Acts 12:4 Acts 12:4And when he had apprehended him, he put him in prison, and delivered him to four squads of soldiers to keep him; intending after Easter to bring him forth to the people.
American King James Version×, where the error was made. The New King James Version, and virtually all other translations, correct this mistake.
Another serious mistake in the King James and New King James versions is in 1 John 5:7-8 1 John 5:7-8  For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.
 And there are three that bear witness in earth, the Spirit, and the water, and the blood: and these three agree in one.
American King James Version×. The latter part of verse 7 and first part of verse 8 did not appear in the Greek texts for the first 1,000 years after the Scriptures were completed. Around the year 500 this portion appeared in the Latin version known as the Vulgate. Apparently the insertion was an attempt to bolster the then-controversial belief in the Trinity. The words added are as follows: "in heaven: the Father, the Word, and the Holy Spirit; and these three are one. And there are three that bear witness on earth."
None of the Greek manuscripts of the New Testament up to the year 1300 contain these words. "The textual evidence is all against 1 John 5:7 1 John 5:7For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.
American King James Version×. Of all the Greek manuscripts, there are only two which contain it. These two manuscripts are of very late dates, one from the fourteenth or fifteenth century and the other from the sixteenth century. Both clearly show this verse to be translated from the Latin" (Neil Lightfoot, How We Got the Bible, 1963, pp. 57-58).
Apparently monks who copied the Greek New Testament text in the 14th or 15th century added this verse from the Vulgate. Even the Catholic Jerusalem Bible admits this verse is not authentic and has left it out. Notes in the Jerusalem Bible explain that this was a marginal note in one of the copies of the Vulgate that was added to the late Greek manuscripts already mentioned.
The verse from 1 John 5:7 1 John 5:7For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.
American King James Version×should read, as hundreds of the oldest Greek texts and most modern translations read: "In fact there are three witnesses, the Spirit, the water, and the blood; and these three are in agreement" (Revised English Bible). This refers to the witness of Jesus Christ being the Son of God (1 John 5:5 1 John 5:5Who is he that overcomes the world, but he that believes that Jesus is the Son of God?
American King James Version×).