Contradiction with Matthew 28:19-20
Jesus commands his disciples to go and teach all nations, which could contradict Acts 18:20 where Paul is sought to stay longer in one place and teach.
Matthew 28:19-20: Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: [teach...: or, make disciples, or, Christians of all nations]
Contradiction with Mark 16:15
Jesus instructs to "Go ye into all the world, and preach the gospel to every creature," potentially conflicting with remaining in one location as suggested in Acts 18:20.
Mark 16:15: And he said unto them, Go ye into all the world, and preach the gospel to every creature.
Contradiction with John 4:35
Jesus speaks of the fields being ready for harvest, implying a sense of urgency in spreading the message, contrasted with a prolonged stay as seen in Acts 18:20.
John 4:35: Say not ye, There are yet four months, and [then] cometh harvest? behold, I say unto you, Lift up your eyes, and look on the fields; for they are white already to harvest.
Contradiction with Acts 1:8
The mandate to be witnesses "unto the uttermost part of the earth" may seem at odds with settling in one place as implied in Acts 18:20.
Acts 1:8: But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judaea, and in Samaria, and unto the uttermost part of the earth. [power...: or, the power of the Holy Ghost coming upon you]