Changes

A quick reading of the Luke passage makes it seem as if Jesus appeared to the disciples just as they received the report of his appearing on the road to Emmaus, then spoke to them for a while, led them out to Bethany and ascended to heaven. However, Luke is compressing multiple events together (see the article from Tekton below for more on this). As Luke records in his second book, Acts, Jesus appeared to the disciples several times over a forty-day period ([http://www.biblegateway.com/passage/?search=Acts+1:3 Acts 1:3]). The meeting in Galilee that Matthew refers to probably occurred after Jesus first met the disciples in Jerusalem, i.e. Luke 24:44 and/or 24:45 refer to separate events from Jesus' appearance in 24:36-43. Also, John records a meeting in Galilee that took place after Jesus' appearing in Jerusalem ([http://www.biblegateway.com/passage/?search=John+21:1 John 21:1]).

The article below from Apologetics Press hypothesizes that Jesus had to meet the disciples in Jerusalem first since they didn't believe the reports from the women who had seen Jesus.

Jesus' instruction to remain in Jerusalem was probably given closer to the time of his ascension and after the meetings in Galilee ([http://www.biblegateway.com/passage/?search=Acts+1:4-5 Acts 1:4-5] is consistent with this).