Every verse in Quran was revealed on the Prophet Muhammad (SAWA) and he conveyed it exactly as it was revealed. The Prophet is infallible and he is the most truthful person. Whatever he conveyed was from Allah with out any doubt.
Jesus was never killed nor crucified by his enemies who did try to commit that crimes, but they failed because Allah (SWT) made the person who informed the enemies of Jesus to catch and kill him, Allah made him look like Jesus in shape, and saved Jesus and raised him to the sky. The enemies of Jesus killed and crucified that person (the informer) not Jesus.
This fact does not harm the validity of the real teachings of Christianity which in fact never said that Jesus was crucified, but it does invalidate the false claims of the enemies of Jesus.