Contradiction with Matthew 24:36
Acts 3:20 speaks of sending Jesus Christ, whom heaven must receive. Matthew 24:36 says that no one knows the day or hour of His coming, not even Jesus, contradicting the certainty implied in Acts 3:20.
Matthew 24:36: But of that day and hour knoweth no [man], no, not the angels of heaven, but my Father only.
Contradiction with 2 Thessalonians 2:3
Acts 3:20 implies Christ's sending will happen when certain conditions are met, but 2 Thessalonians 2:3 warns that there will first be a falling away and the revealing of the man of sin, suggesting conditions contrary to Acts 3:20.
2 Thessalonians 2:3: Let no man deceive you by any means: for [that day shall not come], except there come a falling away first, and that man of sin be revealed, the son of perdition;
Contradiction with 1 Thessalonians 5:2
Acts 3:20 suggests a planned sending of Christ, whereas 1 Thessalonians 5:2 says the day of the Lord will come like a thief in the night, implying it will be unexpected.
1 Thessalonians 5:2: For yourselves know perfectly that the day of the Lord so cometh as a thief in the night.
Contradiction with Revelation 22:12
Acts 3:20 involves sending Jesus, but Revelation 22:12 indicates He comes quickly and on His own initiative, without mentioning any sending by others.
Revelation 22:12: And, behold, I come quickly; and my reward [is] with me, to give every man according as his work shall be.