Not too terribly long ago, A.L. sent me this old chestnut posed by a skeptic:

What did Jesus drink on the cross?

They gave him vinegar to drink, mingled with gall. - Matthew 27:34

And they gave him to drink, wine mingled with myrrh.- Mark 15:23

Interpreted: Here are two different authors' account of the same event.... Jesus on the cross. The first is Matthew saying that they gave Jesus to drink vinegar (old wine) mixed with gall, which is a product that comes from the oak tree. It is used in inks and medicines.

The second verse is from Mark, and it says wine mixed with myrrh, which is a gum resin used in the making of incense. Mark clearly wrote his gospel first, and Matthew must have not been clear on what Mark meant.

Would you argue that gall and myrrh is the same thing??

As a matter of fact, we would. "Gall" is a general term for anything that is bitter. (The Hebrew behind the Psalm word can mean poison, but also meant gall or hemlock.) Myrrh was a bitter substance. Some (even Raymond Brown) deny that this is possible (though even he did not give a reason for saying so!), but let's look at the original Greek word used by Matt:

5521. chole, khol-ay'; fem. of an equiv. perh. akin to the same as G5514 (from the greenish hue); "gall" or bile, i.e. (by anal.) poison or an anodyne (wormwood, poppy, etc.):--gall.

It's used in one other place in the NT, Acts 8:23 -

For I see that you are full of bitterness and captive to sin.

Hmm, so was Simon full of something from an oak tree? Hardly. Chole is manifestly used in both verses in a non-technical sense of something generally bitter. As for that idea that Matthew didn't know what "myrrh" was...it wins my Golden Duh Award. Matt uses a different linguistic form of the same Greek word in Matt. 2:11 re a gift brought by the wise men. (That's granting the assumption, of course, that Mark was Matt's source - which I do not agree with.)

But why did Matt use this general word rather than the specific "myrrh"? Two reasons are possible. First, because he already used the word in 2:11 to refer to a gift, and something pleasant, and did not want to invoke a contrary association. Second, Matt was probably engaging in a bit of typological midrash here, as he used the same word that is found in the LXX version of Psalms 69:21 - "They put gall in my food and gave me vinegar for my thirst." We have, at any rate, no cause to suspect error on anyone's part.