The gamma and bessel functions do not support complex arguments.
Coordinates specified as "time" wrap at 24 hours.
Parametric curves: The 'nohidden3d' option to exempt individual plots from the global setting 'set hidden3d' does not work for parametric curves. Iteration inside a plot command does not work for parametric curves.
X11 terminal: It is difficult to select UTF-8 fonts. Only one color palette at a time is active for any given x11 plot window. This means that multiplots whose constituent plots use different palettes will not display correctly in x11.
Qt terminal: 3D rotation of polygons and surfaces can be slow; this is strongly affected by the Qt rendering mode (see Qt documentation).
The raise and lower functions are unreliable.