Rotationally enhanced red giant stars are astrophysically interesting but rare. In this paper, we present a catalogue of 3217 active red giant candidates in the APOGEE DR16 (Apache Point Observatory Galactic Evolution Experiment – Data Release 16) survey. We use a control sample in the well-studied Kepler fields to demonstrate a strong relationship between rotation and anomalies in the spectroscopic solution relative to typical giants. Stars in the full survey with similar solutions are identified as candidates. We use v sin i measurements to confirm that 50 ± 1.2 per cent of our DR16 candidates are rotationally enhanced (v sin i > 5 km s−1), compared to 4.9 ± 0.2 per cent in the Kepler control sample. In both, the Kepler control sample and a control sample from DR16, we find that there are 3–4 times as many giants rotating with intermediate velocities of 5 < v sin i < 10 km s−1 compared to velocities of v sin i > 10 km s−1, the traditional threshold for rapid rotation for red giants. The vast majority of intermediate rotators are not spectroscopically anomalous. We use binary diagnostics from APOGEE and Gaia to infer a binary fraction of 73 ± 2.4 per cent among the confirmed rotationally enhanced giants in DR16. We identify a significant bias in the reported metallicity for DR16 candidates with complete spectroscopic solutions, with a median offset of −0.37 dex in [M/H] from a control sample. As such, up to 10 per cent of stars with reported [M/H]<−1 are not truly metal poor. Finally, we use Gaia data to identify a subpopulation of main-sequence photometric binaries erroneously classified as giants. [ABSTRACT FROM AUTHOR]