Psalm12:6And the words of the LORD are flawless, like silver purified in a crucible, like gold refined seven times. NIVI am a bit laid back in my choice of word especially the use of the word ‘error’ because the bible is INFALLIBLE (trustworthy) and INERRANT(without error) but the men who scripted it or recorded it are not without error in their writing. They are humans prone to error just like you and me. The original autographs written by the direct recipient as  inspired by the Holy Spirit and those original writings of Paul, Apostles, prophet Isaiah, Jeremiah, Daniel etc were ERROR FREE. Very perfect and accurate, 2Pet1:21, 2Tim3:16.

However, in the course of time after the prophets and apostles died, their writings were moved from place to place in a bid to preserve them. When the church was persecuted under emperors like Decius, Diocletian and Nero, the original writings of the Apostles were burnt but before they were burnt, Christians of that age hurriedly copied from the original autographs and you can be very sure that in that kind of circumstance, there would be error.
Even before persecution arose, some of the early church fathers have started copying from the original autographs because the original autographs were almost destroyed because of the quality of writing materials. In order to preserve Apostolic & prophetic writings, there was so much copying and re copying by scribes. The errors became more pronounced during the persecution years. Nero ordered the burning of some part of Rome so that he can implicate Christians. Christianity has gone through difficult times and that affected transmission of the canon scriptures.

Respite came under emperor Constantine. He ordered Eusebius to make copies of the bible available because he embraced Christianity. It was under this emperor that the standardization of the written manuscripts that were copied from the original started. Do not forget that the original autographs had been burnt while some decayed or got missing in transit so the scribes had to work with some of the imperfect copies that were fraught with errors. There were two scribal schools that existed:
(a) Talmudic- -500A.D.
(b) Masoretic—500-1000A.D.
The Masoretic text are more reliable. However,  after the era of the Masoretes, copying and re copying of bible continued.
Also, the different manuscripts that were copied from the original autographs were in different locations so it took about 1500 years to compile the 66 books of the bible. This story is abridged but I believe you have an idea on how errors found their way into the bible. Get it clear, the error didn’t come from the Holy Spirit or Prophets&Apostles who received the inspiration of the bible but from the scribes who hastily copied it from one manuscripts to another.
ADDENDUM
Let me chip this in about Islam. There are two types of Jihad that Islam has launched against Christianity and the bible:
1-Physical Jihad: Which involves brutal killings and destruction of Christians and Christian historic sites just to denigrate Christianity and rubbish her history.
2- INTELLECTUAL JIHAD: This type of Jihad is what usuf Adepoju* of ACADIP(check google) is doing. They look for little errors in the bible to discredit Christianity and bible. They have converted some Christians to Islam because they showed them some of these things and they agreed with them hook line and sinker. The tombs of some Old testament saints have become mosques today just to discredit the bible and validate Koran. You see, Christians need to be taught the history of their faith and their book so that they won’t be swayed by waves of doctrines and heresies especially in these days of intellectual Jihad. Pastors must go for training and devote enough teaching time to their members. We got saved by preaching but we grow through in-depth teaching.
TYPES OF SCRIBAL ERRORS
(a) UNINTENTIONAL ERROR
(b)INTENTIONAL ERROR
UNINTENTIONAL ERROR
These errors came to be as a result of the imperfections of the scribes due to health, impatience, human faculty/ reasoning, bad eye and wrong divisions of words.
FORMS OF UNINTENTIONAL ERROR
1- Omissions of letters, words and whole lines when an astigmatic eye jumped from one group of letter or words to a similar group. This error is caused by words with similar ending called HOMEOTELEUTON.
2-When only one letter is missing, the error is called HAPLOGRAPHY.
3-When the eye picked up the same letter or word twice, it was called DITTOGRAPHY. For example, “whom do you want me to release for you, Jesus Barabbas or Jesus?” (Matthew27:17). You can see repetition of the word JESUS’.

4- Transposition. This is the reversal of position of two letters or words. The technical term for this is known as METATHESIS. For example, Ahaziah became king at the age of 42 years as recorded in 2Chron22:2 and the same Ahaziah became king at 22years in 2Kings8:26. The same type of error played out in 1Kings4:26 where we were told that Solomon had 40,000 stalls of horses but in 2Chron9:25 the same Solomon had 4,000 stalls of horses. That is a transpositional error. 

5- Errors of the ear occurred only when manuscript were copied by a scribe listening to a reader. This may explain why some manuscripts(after 5th Century) read Kamelos rope instead of Kamëlos (a camel) in Mathew19:24, Kauthasomai(he burns) instead of Kauchasomai( he boasts) in 1Cor13:3.
6- Errors of memory are not so numerous but occasionally a scribe forgot the precise word in a passage and substituted a synonym. He may have been influenced by a parallel passage or truth as in the case of Eph5:9, possibly confused with Galatians5:22, as well as the addition to Hebrews9:22(AV) of “…there is no remission (of sins).”
7- Errors of judgment are generally ascribed to dim lighting and poor eyesight at the occasion of copying the manuscript. At such instances, marginal notations were incorporated into the text perhaps by a sleepy scribe. This is the cause for variant reading in John5:4, 2Cor8:4-5.
8-Errors of writing are attributed to scribes who due to imperfect style or accident wrote indistinctly.
I’ll stop here for now. Now I believe you know why some inconsistencies exist in biblical account. No matter the scribal error, miraculously the teachings and doctrines of the bible remain untampered with.