The Comedy of Errors is Shakespeare's shortest play. Macbeth is his shortest tragedy.
It is, however, worth bearing in mind that the versions of Shakespeare's plays that have been passed down to us through the quartos and Folio derive from various manuscript sources at various removes authorial and theatrical manuscripts. Some texts may derive from scripts that were cut for performance (Macbeth is a likely candidate) whilst others may represent the original authorial texts, prior to theatrical cutting or censorship.